CA2595465A1 - Method of analyzing phosphorous acid, fosetyl-al or both simultaneously - Google Patents
Method of analyzing phosphorous acid, fosetyl-al or both simultaneously Download PDFInfo
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- CA2595465A1 CA2595465A1 CA002595465A CA2595465A CA2595465A1 CA 2595465 A1 CA2595465 A1 CA 2595465A1 CA 002595465 A CA002595465 A CA 002595465A CA 2595465 A CA2595465 A CA 2595465A CA 2595465 A1 CA2595465 A1 CA 2595465A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/62—Detectors specially adapted therefor
- G01N30/72—Mass spectrometers
- G01N30/7233—Mass spectrometers interfaced to liquid or supercritical fluid chromatograph
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/62—Detectors specially adapted therefor
- G01N30/72—Mass spectrometers
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Abstract
Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 5 mg/kg of a sample, comprising the following steps: a) preparation of the sample ; b) optional dilution of the sample prepared ; c) direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC) /tandem mass spectrometry (MS/MS) .
Description
METHOD OF ANALYZING PHOSPHOROUS ACID, FOSETYL-AL
OR BOTH SIMULTANEOUSLY
DESCRIPTION
The present invention relates to the field of pesticidal compound analysis.
Such methods are useful for monitoring the behaviour of such pesticidal compounds once they have been applied, and such methods are also useful during marketing authority procedures for such pesticidal compounds.
The compounds that can be analyzed by means of the method of analysis according to the invention are compounds that are useful for the protection of plants and also some of the compounds that are metabolites of these biologically active compounds. Some of these metabolites can also exhibit biological activities.
Methods for analyzing pesticidal compounds are known. In particular, an analytical method for determining the fosetyl-Al residue and its main metabolite, phosphorous acid, in drinking water or in surface water is known.
Such a known method uses (trimethylsilyl)diazomethane (TMSD) as a derivatizing agent.
Generally, such a method comprises the following steps:
- concentration of the water samples ;
- derivatization with (trimethylsilyl)diazomethane of an aliquot of the concentrated sample (substitution of a hydrogen atom with a methyl group) ;
- purification of the derivatized sample by liquid-liquid partition with dichloromethane.
The analysis is carried out by gas chromatography on a semi-capillary column by means of a flame photometric detector (or FPD) in the phosphorous mode and the quantification takes external standards as reference. The use of a thermionic detector is also possible.
This known method is carried out according to Scheme 1 below:
OR BOTH SIMULTANEOUSLY
DESCRIPTION
The present invention relates to the field of pesticidal compound analysis.
Such methods are useful for monitoring the behaviour of such pesticidal compounds once they have been applied, and such methods are also useful during marketing authority procedures for such pesticidal compounds.
The compounds that can be analyzed by means of the method of analysis according to the invention are compounds that are useful for the protection of plants and also some of the compounds that are metabolites of these biologically active compounds. Some of these metabolites can also exhibit biological activities.
Methods for analyzing pesticidal compounds are known. In particular, an analytical method for determining the fosetyl-Al residue and its main metabolite, phosphorous acid, in drinking water or in surface water is known.
Such a known method uses (trimethylsilyl)diazomethane (TMSD) as a derivatizing agent.
Generally, such a method comprises the following steps:
- concentration of the water samples ;
- derivatization with (trimethylsilyl)diazomethane of an aliquot of the concentrated sample (substitution of a hydrogen atom with a methyl group) ;
- purification of the derivatized sample by liquid-liquid partition with dichloromethane.
The analysis is carried out by gas chromatography on a semi-capillary column by means of a flame photometric detector (or FPD) in the phosphorous mode and the quantification takes external standards as reference. The use of a thermionic detector is also possible.
This known method is carried out according to Scheme 1 below:
2 O + 0 CH3-CH2-O-P-O Al - 3 CH3-CH2-O-P-OH + Al I I
H H
H H
3 fosetyl-Al O TMSD II
H derivatisation I
H
methy Iethy I phosphonate HO-P -OH TMSD
H derivatisation H
phosphorous acid dimethylphosphonate With this method, the limits of detection (LODs) are as follows:
- for fosetyl-Al:
- 0.05 g/I for drinking water (mineral or mains water) ;
- 0.05 g/I for surface water (river water) ;
- for phosphorous acid:
- 0.7 g/I for drinking water (mineral or mains water) ;
- 2.5 g/I for surface water (river water).
With this method, the limits of quantification (LOQs) are as follows:
- for fosetyl-Al:
- 0.1 g/I for drinking water (mineral or mains water) ;
- 1 g/I for surface water (river water) ;
- for phosphorous acid:
- 2.0 (g/l for drinking water (mineral or mains water) ;
H derivatisation I
H
methy Iethy I phosphonate HO-P -OH TMSD
H derivatisation H
phosphorous acid dimethylphosphonate With this method, the limits of detection (LODs) are as follows:
- for fosetyl-Al:
- 0.05 g/I for drinking water (mineral or mains water) ;
- 0.05 g/I for surface water (river water) ;
- for phosphorous acid:
- 0.7 g/I for drinking water (mineral or mains water) ;
- 2.5 g/I for surface water (river water).
With this method, the limits of quantification (LOQs) are as follows:
- for fosetyl-Al:
- 0.1 g/I for drinking water (mineral or mains water) ;
- 1 g/I for surface water (river water) ;
- for phosphorous acid:
- 2.0 (g/l for drinking water (mineral or mains water) ;
- 4.0 (g/l for surface water (river water).
This known method of analysis has been used for the following substrates:
mineral water, mains water and water from the Rhone river. The method of analysis has been validated for various types of water, by analysis of non treated control samples enriched in fosetyl-Al and in phosphorous acid to the limits of quantification and to 10 times these limits.
The analysis of these enriched samples gives recovery rate values for fosetyl-Al or for phosphorous acid, which are compared with the expected theoretical values.
As another known method of analysis, mention may be made of a method for analyzing fosetyl-Al or phosphorous acid residues present in soils taken in Chazay d'Azergues (France), in Goch (Germany) and in Seville (Spain).
This method itself also uses (trimethylsilyl)diazomethane. It is also carried out according to Scheme 1.
In this course of this method, the fosetyl-Al and phosphorous acid residues are extracted from the soil samples by agitation in the presence of an ammonia buffer solution, and then the cations that are present are removed from the extracts by means of an ion exchange resin and the water is evaporated from the samples. Finally, the extracts obtained are derivatized by the action of (trimethylsilyl)diazomethane.
Subsequently, the quantification is carried out by gas chromatography on a semi-capillary column using a flame photometric detector (in the phosphorous mode) with an external standard.
The limit of quantification (LOQ) of this method is 0.100 mg/kg for each of the compounds.
The control samples were enriched in fosetyl-Al or in phosphorous acid up to the limit of quantification and also up to 100 times this limit.
Another known method for analyzing residues concerns the analysis of fosetyl-Al and phosphorous acid residues in plant samples, derived both from fruits and from vegetables.
This method itself also uses (trimethylsilyl)diazomethane. It is also carried out according to Scheme 1.
In the course of this method, the fosetyl-Al and phosphorous acid residues are extracted from the plant samples by milling in a mixture of water and acetonitrile. The extracts are subsequently purified using a C18 cartridge and are then derivatized by the action of (trimethylsilyl)diazomethane.
Subsequently, the quantification is carried out by gas chromatography on a semi-capillary column using a flame photometric detector (in the phosphorous mode) with an external standard.
The limit of quantification of this known method is 0.50 mg/kg for each of the products, with the exception of hop, for which this limit is 2.0 mg/kg for fosetyl-Al and 20.0 mg/kg for phosphorous acid.
This method has been used on samples of bunches of grapes, of oranges, of bananas, of strawberries, of lettuce and of cucumbers. The control samples were enriched, in particular up to the limit of quantification.
Yet another known method for analyzing residues concerns the analysis of fosetyl-Al or phosphorous acid residues in animal tissues or products of animal origin, such as milk, bovine meat, bovine kidneys, bovine liver or eggs.
According to this study, the residues of compounds to be analyzed are extracted from the samples by double milling in a water/acetonitrile mixture (50/50, 20/80 for milk).
An aliquot of the extract is subsequently purified by means of a C18 cartridge (except for milk).
The purified extract is subsequently derivatized with a solution of TMSD.
This method of analysis also follows Scheme 1.
The quantification is carried out by gas chromatography on a DB Wax column using a flame photometric detector in the phosphorous mode.
The limits of quantification are as follows:
- 0.50 mg/kg for fosetyl-Al and phosphorous acid in bovine meat, bovine kidney, bovine liver and eggs ;
- 0.10 mg/kg for fosetyl-Al and phosphorous acid in milk.
For this method, non treated control samples were prepared and analyzed, along with samples enriched to the limit of quantification and also to several times this limit.
The known methods of analysis that have just been mentioned are in accordance with the provisions of European directive No. 46 from 1996 (96/46/EC of 16 July 1996), in particular with respect to the following characteristics:
- for each of the substrates and each level:
- the mean of the recovery rates should be between 70 and 110% ;
- the repeatability, expressed as variation coefficient (ratio of the standard deviation to the mean for the sample concerned, expressed as a percentage) should be at most 20% ;
- for each of the substrates, the total variation coefficient (all levels included) should
This known method of analysis has been used for the following substrates:
mineral water, mains water and water from the Rhone river. The method of analysis has been validated for various types of water, by analysis of non treated control samples enriched in fosetyl-Al and in phosphorous acid to the limits of quantification and to 10 times these limits.
The analysis of these enriched samples gives recovery rate values for fosetyl-Al or for phosphorous acid, which are compared with the expected theoretical values.
As another known method of analysis, mention may be made of a method for analyzing fosetyl-Al or phosphorous acid residues present in soils taken in Chazay d'Azergues (France), in Goch (Germany) and in Seville (Spain).
This method itself also uses (trimethylsilyl)diazomethane. It is also carried out according to Scheme 1.
In this course of this method, the fosetyl-Al and phosphorous acid residues are extracted from the soil samples by agitation in the presence of an ammonia buffer solution, and then the cations that are present are removed from the extracts by means of an ion exchange resin and the water is evaporated from the samples. Finally, the extracts obtained are derivatized by the action of (trimethylsilyl)diazomethane.
Subsequently, the quantification is carried out by gas chromatography on a semi-capillary column using a flame photometric detector (in the phosphorous mode) with an external standard.
The limit of quantification (LOQ) of this method is 0.100 mg/kg for each of the compounds.
The control samples were enriched in fosetyl-Al or in phosphorous acid up to the limit of quantification and also up to 100 times this limit.
Another known method for analyzing residues concerns the analysis of fosetyl-Al and phosphorous acid residues in plant samples, derived both from fruits and from vegetables.
This method itself also uses (trimethylsilyl)diazomethane. It is also carried out according to Scheme 1.
In the course of this method, the fosetyl-Al and phosphorous acid residues are extracted from the plant samples by milling in a mixture of water and acetonitrile. The extracts are subsequently purified using a C18 cartridge and are then derivatized by the action of (trimethylsilyl)diazomethane.
Subsequently, the quantification is carried out by gas chromatography on a semi-capillary column using a flame photometric detector (in the phosphorous mode) with an external standard.
The limit of quantification of this known method is 0.50 mg/kg for each of the products, with the exception of hop, for which this limit is 2.0 mg/kg for fosetyl-Al and 20.0 mg/kg for phosphorous acid.
This method has been used on samples of bunches of grapes, of oranges, of bananas, of strawberries, of lettuce and of cucumbers. The control samples were enriched, in particular up to the limit of quantification.
Yet another known method for analyzing residues concerns the analysis of fosetyl-Al or phosphorous acid residues in animal tissues or products of animal origin, such as milk, bovine meat, bovine kidneys, bovine liver or eggs.
According to this study, the residues of compounds to be analyzed are extracted from the samples by double milling in a water/acetonitrile mixture (50/50, 20/80 for milk).
An aliquot of the extract is subsequently purified by means of a C18 cartridge (except for milk).
The purified extract is subsequently derivatized with a solution of TMSD.
This method of analysis also follows Scheme 1.
The quantification is carried out by gas chromatography on a DB Wax column using a flame photometric detector in the phosphorous mode.
The limits of quantification are as follows:
- 0.50 mg/kg for fosetyl-Al and phosphorous acid in bovine meat, bovine kidney, bovine liver and eggs ;
- 0.10 mg/kg for fosetyl-Al and phosphorous acid in milk.
For this method, non treated control samples were prepared and analyzed, along with samples enriched to the limit of quantification and also to several times this limit.
The known methods of analysis that have just been mentioned are in accordance with the provisions of European directive No. 46 from 1996 (96/46/EC of 16 July 1996), in particular with respect to the following characteristics:
- for each of the substrates and each level:
- the mean of the recovery rates should be between 70 and 110% ;
- the repeatability, expressed as variation coefficient (ratio of the standard deviation to the mean for the sample concerned, expressed as a percentage) should be at most 20% ;
- for each of the substrates, the total variation coefficient (all levels included) should
5 be at most 20%.
Another known method for analyzing fosetyl-AI is described in an article entitled Rapid determination of fosetyl-Al residues in lettuce by liquid chromatography/electrospray tandem mass spectrometry (Hernandez et al., Journal of AOAC International, Vol. 86, No. 4, 2003).
The method described concerns the quantification of fosetyl-Al residues in plant samples that are derived from lettuce. The method requires a step consisting of extraction with water by means of a high-speed mixer, followed by the injection of a 5-fold diluted extract into a liquid-phase chromatograph.
The fosetyl-Al is therefore quantified by liquid chromatography coupled to electrospray tandem mass spectrometry after addition of tetrabutylammonium acetate as an.ionic pairing agent.
The analysis of samples of lettuce enriched at 2 and 0.2 mg/kg is reported.
The limit of quantification is 0.2 mg/kg, whereas the limit of detection of fosetyl-Al is 0.05 mg/kg.
However, many of these known methods of analysis require a chemical derivatization step.
Such an additional step complicates the analysis and very substantially prolongs the duration thereof. Furthermore, the implementation of this step requires specific expertise and increases the financial cost of these methods.
In addition, during such a derivatization step, the derivatizing agents used, which may be TMSD, diazomethane or other alternative derivatizing agents, are reactants which, in addition to their high cost, present considerable risks when they are used. Among the risks encountered when using such derivatizing agents, mention may be made of their toxicity and also their explosiveness. The use of such agents also results in a high cost.
Moreover, these known methods comprise many handling steps (evaporations, re-dissolutions, sample transfers) increasing, accordingly, the loss and dissemination of the compounds to be analyzed. Such a dissemination of compounds can also pose the problem of its environmental impact, in particular when the effluents derived from these methods of analysis are retreated.
Furthermore, these known methods have the major drawback of not being specific for particular compounds. This lack of specificity can result in compounds for which the protection and
Another known method for analyzing fosetyl-AI is described in an article entitled Rapid determination of fosetyl-Al residues in lettuce by liquid chromatography/electrospray tandem mass spectrometry (Hernandez et al., Journal of AOAC International, Vol. 86, No. 4, 2003).
The method described concerns the quantification of fosetyl-Al residues in plant samples that are derived from lettuce. The method requires a step consisting of extraction with water by means of a high-speed mixer, followed by the injection of a 5-fold diluted extract into a liquid-phase chromatograph.
The fosetyl-Al is therefore quantified by liquid chromatography coupled to electrospray tandem mass spectrometry after addition of tetrabutylammonium acetate as an.ionic pairing agent.
The analysis of samples of lettuce enriched at 2 and 0.2 mg/kg is reported.
The limit of quantification is 0.2 mg/kg, whereas the limit of detection of fosetyl-Al is 0.05 mg/kg.
However, many of these known methods of analysis require a chemical derivatization step.
Such an additional step complicates the analysis and very substantially prolongs the duration thereof. Furthermore, the implementation of this step requires specific expertise and increases the financial cost of these methods.
In addition, during such a derivatization step, the derivatizing agents used, which may be TMSD, diazomethane or other alternative derivatizing agents, are reactants which, in addition to their high cost, present considerable risks when they are used. Among the risks encountered when using such derivatizing agents, mention may be made of their toxicity and also their explosiveness. The use of such agents also results in a high cost.
Moreover, these known methods comprise many handling steps (evaporations, re-dissolutions, sample transfers) increasing, accordingly, the loss and dissemination of the compounds to be analyzed. Such a dissemination of compounds can also pose the problem of its environmental impact, in particular when the effluents derived from these methods of analysis are retreated.
Furthermore, these known methods have the major drawback of not being specific for particular compounds. This lack of specificity can result in compounds for which the protection and
6 PCT/EP2006/001433 quantification characteristics are similar, not being differentiated. Other known methods have the disadvantage of only allowing the analysis of fosetyl-AI alone, without being able to carry out the simultaneous analysis of phosphorous acid, for example.
Some of the known methods are described only for particular matrices ; for example, one already known method concerns only particular plant tissues derived from lettuce.
Finally, these known methods do not make it possible to achieve certain stricter limits of quantification, in particular the limits of quantification ensuing from recent regulations, for example directive 96/46/EC of 16 July 1996.
A method of analysis has now been found which makes it possible to provide a solution to these problems or to prevent these drawbacks related to the known methods.
Thus, the present invention relates to a method for analyzing residues of pesticidal compounds.
The method according to the invention may be suitable for the analysis of pesticidal compounds, whether they are fungicides, herbicides, insecticides or growth regulators.
Advantageously, the method of analysis according to the invention is used for analyzing residues of fungicidal compounds.
Particularly advantageously, the method of analysis according to the invention is used for analyzing fosetyl-Al residues and phosphorous acid residues.
fosetyl-Al is a fungicidal compound of phosphonic acid type, the chemical name of which is ethyl hydrogen phosphonic acid aluminium salt, having the formula O \\
Et~ ~P Al I
H
Phosphorous acid has the formula H3PO3.
Thus, among other advantages, the method of analysis according to the present invention is of great simplicity. Furthermore, this method is direct and it makes it possible to achieve levels of quantification of the pesticidal compounds analyzed that have never before been achieved.
Some of the known methods are described only for particular matrices ; for example, one already known method concerns only particular plant tissues derived from lettuce.
Finally, these known methods do not make it possible to achieve certain stricter limits of quantification, in particular the limits of quantification ensuing from recent regulations, for example directive 96/46/EC of 16 July 1996.
A method of analysis has now been found which makes it possible to provide a solution to these problems or to prevent these drawbacks related to the known methods.
Thus, the present invention relates to a method for analyzing residues of pesticidal compounds.
The method according to the invention may be suitable for the analysis of pesticidal compounds, whether they are fungicides, herbicides, insecticides or growth regulators.
Advantageously, the method of analysis according to the invention is used for analyzing residues of fungicidal compounds.
Particularly advantageously, the method of analysis according to the invention is used for analyzing fosetyl-Al residues and phosphorous acid residues.
fosetyl-Al is a fungicidal compound of phosphonic acid type, the chemical name of which is ethyl hydrogen phosphonic acid aluminium salt, having the formula O \\
Et~ ~P Al I
H
Phosphorous acid has the formula H3PO3.
Thus, among other advantages, the method of analysis according to the present invention is of great simplicity. Furthermore, this method is direct and it makes it possible to achieve levels of quantification of the pesticidal compounds analyzed that have never before been achieved.
7 The method according to the invention is also particularly advantageous from an environmental point of view, and also economically.
In generai, the present invention relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.00005 mg/kg, preferably less than or equal to 0.000005 mg/kg, more preferably less than or equal to 0.0000005 mg/kg of a sample, comprising the following steps:
- preparation of the sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
For the liquid samples analyzed according to the present invention, the limits of quantification can be expressed in mg/I. Those skilled in the art will be able to make the necessary conversions.
The method of analysis according to the invention may comprise a step consisting of dilution of the sample prepared.
The method of analysis according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ; phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al or of phosphorous acid.
Particularly advantageously, the method of analysis according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method of analysis according to the invention can be used for the analysis of samples chosen from plant tissues, preferably a plant matrix with a high water content, a plant matrix with an acidic pH, a dry plant matrix, a fatty plant matrix ; water, preferably mineral water, underground water, mains water or surface water ; soils ; animal products or tissues, preferably milk, eggs, liver, kidneys, fats, muscle ; air ; agrofood products, preferably converted, and human body fluids such as blood and urine.
In generai, the present invention relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.00005 mg/kg, preferably less than or equal to 0.000005 mg/kg, more preferably less than or equal to 0.0000005 mg/kg of a sample, comprising the following steps:
- preparation of the sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
For the liquid samples analyzed according to the present invention, the limits of quantification can be expressed in mg/I. Those skilled in the art will be able to make the necessary conversions.
The method of analysis according to the invention may comprise a step consisting of dilution of the sample prepared.
The method of analysis according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ; phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al or of phosphorous acid.
Particularly advantageously, the method of analysis according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method of analysis according to the invention can be used for the analysis of samples chosen from plant tissues, preferably a plant matrix with a high water content, a plant matrix with an acidic pH, a dry plant matrix, a fatty plant matrix ; water, preferably mineral water, underground water, mains water or surface water ; soils ; animal products or tissues, preferably milk, eggs, liver, kidneys, fats, muscle ; air ; agrofood products, preferably converted, and human body fluids such as blood and urine.
8 For the method of analysis according to the invention, the preparation step can be chosen from an extraction for plant tissues ; soils ; animal products or tissues and converted agrofood products ; optional concentration for water and trapping for air.
Such a concentration step may also be used for other samples.
For the method of analysis according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a first particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.005 mg/kg, preferably less than or equal to 0.00005 mg/kg, more preferably less than or equal to 0.0000005 mg/kg of a water sample, comprising the following steps:
- preparation of the water sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a water sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a water sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a water sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or one of more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a water sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a water sample according to the invention can be used for the analysis of samples chosen from mineral water, underground water, mains water or surface water.
Such a concentration step may also be used for other samples.
For the method of analysis according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a first particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.005 mg/kg, preferably less than or equal to 0.00005 mg/kg, more preferably less than or equal to 0.0000005 mg/kg of a water sample, comprising the following steps:
- preparation of the water sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a water sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a water sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a water sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or one of more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a water sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a water sample according to the invention can be used for the analysis of samples chosen from mineral water, underground water, mains water or surface water.
9 For the method for analyzing a water sample according to the invention the preparation step may be a concentration.
For the method for analyzing a water sample according to the invention, the dilution step may be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a second particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 1 mg/kg, preferably less than or equal to 0.01 mg/kg, more particularly less than or equal to 0.001 mg/kg of a plant tissue sample, comprising the following steps:
- preparation of the plant tissue sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a plant tissue sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a plant tissue sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a plant tissue sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a plant tissue sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a plant tissue sample according to the invention can be used for the analysis of samples chosen from a plant matrix with a high water content, a plant matrix with an acidic pH, a dry plant matrix and a fatty plant matrix.
The method of analysis according to the invention can be used for the analysis of a sample of plants chosen from wheat, barley, potato, cotton, proteinaceous crops, oil-bearing crops, maize, flax, rice, vegetable crops, fruit trees, grapevine and beetroot.
For the method for analyzing a plant tissue sample according to the invention, the preparation step may be an extraction of the plant tissues. This preparation step may also comprise a concentration of the sample.
For the method for analyzing a plant tissue sample according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a third particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 5 mg/kg, preferably less than or equal to 0.05 mg/kg, more particularly less than or equal to 0.005 mg/kg of a soil sample, comprising the following steps:
- preparation of the soil sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a soil sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a soil sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a soil sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a soil sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
The method for analyzing a soil sample according to the invention can be used for the analysis of any type of soil, for example clayey, sandy or chalky soil.
The method for analyzing soil according to the invention can be used for cultivated soils or for bare soils, in particular before a crop or after harvest.
For the method for analyzing a soil sample according to the invention, the preparation step may be an extraction of the soil sample. This preparation step may also comprise a concentration of the sample.
For the method for analyzing a soil sample according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a fourth particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.1 mg/m3, preferably less than or equal to 0.01 mg/m3, more particularly less than or equal to 0.001 mg/m3 of an air sample, comprising the following steps:
- preparation of the air sample;
- optional dilution of the sample prepared;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing an air sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing an air sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing an air sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing an air sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
For the method for analyzing an air sample according to the invention, the preparation step may be a trapping.
For the method for analyzing an air sample according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a fifth particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.00005 mg/kg, preferably less than or equal to 0.000005 mg/kg, more preferably less than or equal to 0.0000005 mg/kg of a sample of a human body fluid, comprising the following steps:
- preparation of the human body fluid sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a sample of a human body fluid according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a sample of a human body fluid according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a sample of a human body fluid according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ; phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a sample of a human body fluid according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a sample of a human body fluid according to the invention can be used for the analysis of a sample chosen from human blood and human urine.
For the method for analyzing a sampie of a human body fluid according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trif(uoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a sixth particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 1 mg/kg, preferably less than or equal to 0.01 mg/kg, more preferably less than or equal to 0.001 mg/kg of a sample of animal products or tissues, comprising the following steps:
- preparation of the sample of animal products or tissues ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a sample of animal products or tissues according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a sample of animal products or tissues according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a sample of animal products or tissues according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ; phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a sample of animal products or tissues according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a sample of animal products or tissues according to the invention can be used for the analysis of a sample chosen from milk, eggs, liver, kidneys, fats and muscle.
For the method for analyzing a sample of animal products or tissues according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
For the method for analyzing a sample of animal products or tissues according to the invention, the preparation step may be an extraction of the animal products or tissues.
This preparation step may also comprise a concentration of the sample.
According to a seventh particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in a converted agrofood product sample. This method for analyzing a converted agrofood product sample according to the invention is similar to the method for analyzing a plant product sample according to the invention, in which the plant product sample is replaced with a converted agrofood product sample.
The various steps and preferences are also similar.
For the various aspects of the invention, in the analysis step, the external standards used are prepared in the presence of a matrix of the same nature as the sample to be analyzed.
The examples which follow are given by way of illustration of the various aspects of the invention. These examples do not limit the scope of the invention. In particular, those skilled in the art will be able to adapt or modify some of the steps of the method of analysis according to the invention according to the specific needs with which they will be confronted. Such modifications or adaptations are part of the scope of the present invention.
Example 1:
This example concerns the analysis of fosetyl-Al and of phosphorous acid using plant tissue samples. The plant matrices are derived from crops: of cucumber, of orange, of lettuce, of grape and of avocado.
Procedure for using the method of analysis according to the invention:
1. Weigh 20.0 g of homogenized plant matrix sample into a 125 ml polypropylene flask.
2. Add 80 ml of the water/acetonitrile mixture (50/50, volume/volume).
3. Mill the sample for 5 minutes using an IKA T25-type mill.
4. Centrifuge for 5 minutes at 3600 rpm at 5 C.
5. Transfer the supernatant into a 200 ml volumetric flask.
6. Take up the pellet with 80 ml of the water/acetonitrile mixture (50/50, volume/volume).
7. Mill the sample again for 5 minutes.
8. Centrifuge for 5 minUtes at 3600 rpm at 5 C.
9. Transfer the supernatant into the 200 ml volumetric flask.
For the method for analyzing a water sample according to the invention, the dilution step may be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a second particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 1 mg/kg, preferably less than or equal to 0.01 mg/kg, more particularly less than or equal to 0.001 mg/kg of a plant tissue sample, comprising the following steps:
- preparation of the plant tissue sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a plant tissue sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a plant tissue sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a plant tissue sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a plant tissue sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a plant tissue sample according to the invention can be used for the analysis of samples chosen from a plant matrix with a high water content, a plant matrix with an acidic pH, a dry plant matrix and a fatty plant matrix.
The method of analysis according to the invention can be used for the analysis of a sample of plants chosen from wheat, barley, potato, cotton, proteinaceous crops, oil-bearing crops, maize, flax, rice, vegetable crops, fruit trees, grapevine and beetroot.
For the method for analyzing a plant tissue sample according to the invention, the preparation step may be an extraction of the plant tissues. This preparation step may also comprise a concentration of the sample.
For the method for analyzing a plant tissue sample according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a third particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 5 mg/kg, preferably less than or equal to 0.05 mg/kg, more particularly less than or equal to 0.005 mg/kg of a soil sample, comprising the following steps:
- preparation of the soil sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a soil sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a soil sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a soil sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a soil sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
The method for analyzing a soil sample according to the invention can be used for the analysis of any type of soil, for example clayey, sandy or chalky soil.
The method for analyzing soil according to the invention can be used for cultivated soils or for bare soils, in particular before a crop or after harvest.
For the method for analyzing a soil sample according to the invention, the preparation step may be an extraction of the soil sample. This preparation step may also comprise a concentration of the sample.
For the method for analyzing a soil sample according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a fourth particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.1 mg/m3, preferably less than or equal to 0.01 mg/m3, more particularly less than or equal to 0.001 mg/m3 of an air sample, comprising the following steps:
- preparation of the air sample;
- optional dilution of the sample prepared;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing an air sample according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing an air sample according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing an air sample according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ;
phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing an air sample according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
For the method for analyzing an air sample according to the invention, the preparation step may be a trapping.
For the method for analyzing an air sample according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a fifth particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.00005 mg/kg, preferably less than or equal to 0.000005 mg/kg, more preferably less than or equal to 0.0000005 mg/kg of a sample of a human body fluid, comprising the following steps:
- preparation of the human body fluid sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a sample of a human body fluid according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a sample of a human body fluid according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a sample of a human body fluid according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ; phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a sample of a human body fluid according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a sample of a human body fluid according to the invention can be used for the analysis of a sample chosen from human blood and human urine.
For the method for analyzing a sampie of a human body fluid according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trif(uoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
According to a sixth particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 1 mg/kg, preferably less than or equal to 0.01 mg/kg, more preferably less than or equal to 0.001 mg/kg of a sample of animal products or tissues, comprising the following steps:
- preparation of the sample of animal products or tissues ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
The method for analyzing a sample of animal products or tissues according to the invention may comprise a step consisting of dilution of the sample prepared.
The method for analyzing a sample of animal products or tissues according to the invention is suitable for the simultaneous analysis of several pesticidal compounds which may be fungicidal, herbicidal, insecticidal or growth-regulating compounds.
Preferably, the method for analyzing a sample of animal products or tissues according to the invention is used for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ; phosphonic acid or a derivative thereof ; preferably for the analysis of fosetyl or of one or more salts thereof ; more preferably for the analysis of fosetyl-Al.
Particularly advantageously, the method for analyzing a sample of animal products or tissues according to the invention is used for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
Preferably, the method for analyzing a sample of animal products or tissues according to the invention can be used for the analysis of a sample chosen from milk, eggs, liver, kidneys, fats and muscle.
For the method for analyzing a sample of animal products or tissues according to the invention, the dilution step can be carried out in an aqueous solvent, which may be acidified, preferably chosen from formic acid, acetic acid or trifluoroacetic acid ; or in an organic solvent, preferably acetonitrile or methanol, which may be acidified ; or alternatively in a mixture of such solvents.
For the method for analyzing a sample of animal products or tissues according to the invention, the preparation step may be an extraction of the animal products or tissues.
This preparation step may also comprise a concentration of the sample.
According to a seventh particular aspect of the invention, it relates to a method for analyzing one or more pesticidal compounds present in a converted agrofood product sample. This method for analyzing a converted agrofood product sample according to the invention is similar to the method for analyzing a plant product sample according to the invention, in which the plant product sample is replaced with a converted agrofood product sample.
The various steps and preferences are also similar.
For the various aspects of the invention, in the analysis step, the external standards used are prepared in the presence of a matrix of the same nature as the sample to be analyzed.
The examples which follow are given by way of illustration of the various aspects of the invention. These examples do not limit the scope of the invention. In particular, those skilled in the art will be able to adapt or modify some of the steps of the method of analysis according to the invention according to the specific needs with which they will be confronted. Such modifications or adaptations are part of the scope of the present invention.
Example 1:
This example concerns the analysis of fosetyl-Al and of phosphorous acid using plant tissue samples. The plant matrices are derived from crops: of cucumber, of orange, of lettuce, of grape and of avocado.
Procedure for using the method of analysis according to the invention:
1. Weigh 20.0 g of homogenized plant matrix sample into a 125 ml polypropylene flask.
2. Add 80 ml of the water/acetonitrile mixture (50/50, volume/volume).
3. Mill the sample for 5 minutes using an IKA T25-type mill.
4. Centrifuge for 5 minutes at 3600 rpm at 5 C.
5. Transfer the supernatant into a 200 ml volumetric flask.
6. Take up the pellet with 80 ml of the water/acetonitrile mixture (50/50, volume/volume).
7. Mill the sample again for 5 minutes.
8. Centrifuge for 5 minUtes at 3600 rpm at 5 C.
9. Transfer the supernatant into the 200 ml volumetric flask.
10. Adjust to 200 ml using methanol.
11. Centrifuge an aliquot of approximately 10 ml for 10 minutes at 6000 rpm at ambient temperature.
12. Filter the supernatant through a PTFE filter (of the type Acrodisc CR 25 mm, 0.45 m).
13. Dilute the filtrate 5 times using methanol acidified with 0.5% formic acid.
14. Analyze by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS), or LC/MS/MS analysis.
To implement the analysis, the calibration is carried out by external standardization. The standards used must be prepared in a matrix of the same nature as the samples that are the subject of the specific analysis.
Analytical conditions for step 14:
High performance liquid chromatography (HPLC) conditions:
10 Column: Hypercarb, 100 x 3.0 mm, 5 m Precolumn: Phenomenex C18 ODS, 4 x 2.0 mm Mobile phase: water acidified with 0.5%
formic acid/methanol (65/35, volume/volume) isocratic mode
To implement the analysis, the calibration is carried out by external standardization. The standards used must be prepared in a matrix of the same nature as the samples that are the subject of the specific analysis.
Analytical conditions for step 14:
High performance liquid chromatography (HPLC) conditions:
10 Column: Hypercarb, 100 x 3.0 mm, 5 m Precolumn: Phenomenex C18 ODS, 4 x 2.0 mm Mobile phase: water acidified with 0.5%
formic acid/methanol (65/35, volume/volume) isocratic mode
15 Flow rate: 400 l/min Column temperature: ambient Injection volume: 20 i Before the analysis, the chromatographic system is left to stabilize for approximately 2 hours.
Tandem mass spectrometry (MS/MS) conditions:
Detector: triple quadrupole, type API4000 Sciex Instrument Interface: TIS (Turbo Ion Spray) Scan type: MRM (Multiple Reaction Monitoring) mode Polarity: negative Gas inlet pressure: nitrogen: 4 bar air: 7.5 bar air (exhaust): 4 bar Gas flow rate: nebulizing gas (air, GS1):40 turbo gas (air, GS2):60 protective gas (nitrogen, CUR):20 collision gas (nitrogen, CAD):6 High voltage TIS (IS): -4500 V
Source temperature: 600 C
Entry potential (EP): -10 V
Tandem mass spectrometry (MS/MS) conditions:
Detector: triple quadrupole, type API4000 Sciex Instrument Interface: TIS (Turbo Ion Spray) Scan type: MRM (Multiple Reaction Monitoring) mode Polarity: negative Gas inlet pressure: nitrogen: 4 bar air: 7.5 bar air (exhaust): 4 bar Gas flow rate: nebulizing gas (air, GS1):40 turbo gas (air, GS2):60 protective gas (nitrogen, CUR):20 collision gas (nitrogen, CAD):6 High voltage TIS (IS): -4500 V
Source temperature: 600 C
Entry potential (EP): -10 V
16 Collision energy:
Compound Precursor Product Dwell Collision Decluster- Collision ion Q1 ion Q3 time energy ing potential cell exit mass (amu) mass (msec) (CE) (V) potential (amu) (eV) (CXP) M
fosetyl-Al 109.0 80.9 200 -16 -45 -1 109.0 63.0 200 -38 -45 -5 H3PO3 80.9 63.0 600 -38 -55 -1 80.9 78.9 600 -22 -55 -5 When the method of analysis according to the invention is used, steps 1 to 12 concern the preparation of the sample, and step 13 concerns the dilution. Thus, step 14 concerns the LC/MS/MS analysis of the plant matrix sample prepared beforehand and then diluted.
The results obtained from the analysis of various plant matrices are given in detail in the tables below, in which the CV values indicate the coefficient of variation. According to the present invention, the CV values can also correspond to RSD values.
These results were obtained from control samples which were enriched in fosetyl-Al and in phosphorous acid to limits of quantification (0.1 mg/kg for phosphorous acid and 0.01 mg/kg for fosetyl-Al) and to 10 times these limits.
Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.100 83 82 82 91 95 87 7.0 1.000 102 102 101 97 99 100 2.2 Total CV [%] 93 8.9 Cucumber - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 95 96 98 98 95 96 1.6 0.100 106 101 101 99 100 101 2.7 Total CV [%] 99 3.4 Cucumber - fosetyl-Al
Compound Precursor Product Dwell Collision Decluster- Collision ion Q1 ion Q3 time energy ing potential cell exit mass (amu) mass (msec) (CE) (V) potential (amu) (eV) (CXP) M
fosetyl-Al 109.0 80.9 200 -16 -45 -1 109.0 63.0 200 -38 -45 -5 H3PO3 80.9 63.0 600 -38 -55 -1 80.9 78.9 600 -22 -55 -5 When the method of analysis according to the invention is used, steps 1 to 12 concern the preparation of the sample, and step 13 concerns the dilution. Thus, step 14 concerns the LC/MS/MS analysis of the plant matrix sample prepared beforehand and then diluted.
The results obtained from the analysis of various plant matrices are given in detail in the tables below, in which the CV values indicate the coefficient of variation. According to the present invention, the CV values can also correspond to RSD values.
These results were obtained from control samples which were enriched in fosetyl-Al and in phosphorous acid to limits of quantification (0.1 mg/kg for phosphorous acid and 0.01 mg/kg for fosetyl-Al) and to 10 times these limits.
Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.100 83 82 82 91 95 87 7.0 1.000 102 102 101 97 99 100 2.2 Total CV [%] 93 8.9 Cucumber - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 95 96 98 98 95 96 1.6 0.100 106 101 101 99 100 101 2.7 Total CV [%] 99 3.4 Cucumber - fosetyl-Al
17 Quantification Recovery range Means CV
level mg/kg 0.100 65 99 70 78 67 76 18.3 1.000 97 99 101 95 99 98 2.3 Total CV [%] 87 17.3 Orange - phosphorous acid Quantification Recovery range Means CV
level mg/kg 0.010 102 100 98 87 97 97 6.0 0.100 96 95 94 90 86 92 4.5 Total CV [%] 95 5.6 Orange - fosetyl-Al Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.100 82 94 76 79 74 81 9.7 1.000 103 108 98 106 107 104 3.9 Total CV [%] 93 14.7 Lettuce - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 104 98 109 113 114 108 6.2 0.100 102 106 104 107 107 105 2.1 Total CV [%] 106 4.5 Lettuce - fosetyl-Al
level mg/kg 0.100 65 99 70 78 67 76 18.3 1.000 97 99 101 95 99 98 2.3 Total CV [%] 87 17.3 Orange - phosphorous acid Quantification Recovery range Means CV
level mg/kg 0.010 102 100 98 87 97 97 6.0 0.100 96 95 94 90 86 92 4.5 Total CV [%] 95 5.6 Orange - fosetyl-Al Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.100 82 94 76 79 74 81 9.7 1.000 103 108 98 106 107 104 3.9 Total CV [%] 93 14.7 Lettuce - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 104 98 109 113 114 108 6.2 0.100 102 106 104 107 107 105 2.1 Total CV [%] 106 4.5 Lettuce - fosetyl-Al
18 Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.100 96 94 113 100 92 99 8.5 1.000 100 105 104 101 101 102 2.1 Total CV [%] 101 6.0 Grape - phosphorous acid Quantification Recovery range Means CV
level mg/kg 0.010 102 102 95 101 100 100 2.9 0.100 101 102 102 102 100 101 0.9 Total CV [%] 101 2.1 Grape - fosetyi-AI
Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.100 74 77 68 70 75 73 5.1 1.000 110 97 92 103 100 100 6.7 Total CV [%] 87 17.8 Avocado - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 104 95 92 94 93 96 5.0 0.100 88 88 85 89 86 87 1.9 Total CV [%] 91 6.1 Avocado - fosetyl-Al Example 2:
This example also concerns the analysis of fosetyl-Al and of phosphorus acid using plant tissue samples. The plant matrices are derived from wheat crops.
This example repeats the conditions of Example 1 up to step 9, and then steps 10 to 14 of Example I are replaced with the following steps:
level [%] [%] [%]
mg/kg 0.100 96 94 113 100 92 99 8.5 1.000 100 105 104 101 101 102 2.1 Total CV [%] 101 6.0 Grape - phosphorous acid Quantification Recovery range Means CV
level mg/kg 0.010 102 102 95 101 100 100 2.9 0.100 101 102 102 102 100 101 0.9 Total CV [%] 101 2.1 Grape - fosetyi-AI
Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.100 74 77 68 70 75 73 5.1 1.000 110 97 92 103 100 100 6.7 Total CV [%] 87 17.8 Avocado - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 104 95 92 94 93 96 5.0 0.100 88 88 85 89 86 87 1.9 Total CV [%] 91 6.1 Avocado - fosetyl-Al Example 2:
This example also concerns the analysis of fosetyl-Al and of phosphorus acid using plant tissue samples. The plant matrices are derived from wheat crops.
This example repeats the conditions of Example 1 up to step 9, and then steps 10 to 14 of Example I are replaced with the following steps:
19 10. Add I ml of pure formic acid and adjust to 200 ml using methanol.
11. Centrifuge an aliquot of approximately 10 mi for 10 minutes at 6000 rpm at ambient temperature.
12. Dilute the supernatant twice using methanol acidified with 0.5% formic acid.
13. Filter through a PTFE filter (type Acrodisc CR 25 mm, 0.45 m).
14. Analyze by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS), or LC/MS/MS analysis.
For the rest, this example is identical to Example 1.
The results obtained from the analysis of a wheat sample are given in detail in the table below, in which CV indicates the coefficient of variation.
These results were obtained from control samples which were enriched in fosetyl-Al and in phosphorous acid to the limits of quantification (0.1 mg/kg for phosphorous acid and 0.01 mg/kg for fosetyl-Al) and to 10 times these limits.
Quantification Recovery range Means CV
level mg/kgb 0.100 90 94 101 102 103 98 5.8 1.000 77 77 81 79 81 79 2.5 Total CV [%] 89 12.2 Wheat - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 86 92 93. 85 82 88 5.4 0.100 75 79 69 71 71 73 5.5 Total CV [%] 80 10.9 Wheat - fosetyl-Al For these two examples, the results obtained are in accordance with the regulatory provisions (96/46/EC of 16 July 1996).
Furthermore, these results made it possible to attain limits of quantification that are below the limits available with the previously known methods.
These examples also demonstrate the simplicity and the greater safety of the method according to the invention.
Example 3:
This detailed example concerns the analysis of fosetyl-Al and of phosphorous acid using plant tissue samples. This example is a modification M001 to the Analytical Method 00861 for the 10 determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in/on grape, orange, lettuce, cucumber, avocado and wheat by LCMSMS.
Description:
15 Data Requirement:
EU Council Directive 91/414/EEC amended by Commission Directive 96/68/EC
European Commission Guidance Document for Generating and Reporting Methods of Analysis in Support of Pre-Registration Data Requirements for Annex II (Part A, Section 4) and Annex III
(Part A, Section 5) of Directive 91/414, SANCO/3029/99
11. Centrifuge an aliquot of approximately 10 mi for 10 minutes at 6000 rpm at ambient temperature.
12. Dilute the supernatant twice using methanol acidified with 0.5% formic acid.
13. Filter through a PTFE filter (type Acrodisc CR 25 mm, 0.45 m).
14. Analyze by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS), or LC/MS/MS analysis.
For the rest, this example is identical to Example 1.
The results obtained from the analysis of a wheat sample are given in detail in the table below, in which CV indicates the coefficient of variation.
These results were obtained from control samples which were enriched in fosetyl-Al and in phosphorous acid to the limits of quantification (0.1 mg/kg for phosphorous acid and 0.01 mg/kg for fosetyl-Al) and to 10 times these limits.
Quantification Recovery range Means CV
level mg/kgb 0.100 90 94 101 102 103 98 5.8 1.000 77 77 81 79 81 79 2.5 Total CV [%] 89 12.2 Wheat - phosphorous acid Quantification Recovery range Means CV
level [%] [%] [%]
mg/kg 0.010 86 92 93. 85 82 88 5.4 0.100 75 79 69 71 71 73 5.5 Total CV [%] 80 10.9 Wheat - fosetyl-Al For these two examples, the results obtained are in accordance with the regulatory provisions (96/46/EC of 16 July 1996).
Furthermore, these results made it possible to attain limits of quantification that are below the limits available with the previously known methods.
These examples also demonstrate the simplicity and the greater safety of the method according to the invention.
Example 3:
This detailed example concerns the analysis of fosetyl-Al and of phosphorous acid using plant tissue samples. This example is a modification M001 to the Analytical Method 00861 for the 10 determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in/on grape, orange, lettuce, cucumber, avocado and wheat by LCMSMS.
Description:
15 Data Requirement:
EU Council Directive 91/414/EEC amended by Commission Directive 96/68/EC
European Commission Guidance Document for Generating and Reporting Methods of Analysis in Support of Pre-Registration Data Requirements for Annex II (Part A, Section 4) and Annex III
(Part A, Section 5) of Directive 91/414, SANCO/3029/99
20 European Commission Guidance Document for on Residue Analytical Methods, Summary:
The presented residue analytical method modification 00861/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit),avocado (whole fruit), and wheat (grain) by LC/MS/MS.
fosetyl-Al and its metabolite (phosphorous acid) were extracted from the sample material with a mixture of acetonitrile/water (50/50). After centrifugation and dilution of the sample material, the residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation in matrix matched standards The validation set included the determination of the detector linearity, the limit of quantification, the accuracy of the method and the storage stability of sample final extracts.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 Ng/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L.
The presented residue analytical method modification 00861/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit),avocado (whole fruit), and wheat (grain) by LC/MS/MS.
fosetyl-Al and its metabolite (phosphorous acid) were extracted from the sample material with a mixture of acetonitrile/water (50/50). After centrifugation and dilution of the sample material, the residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation in matrix matched standards The validation set included the determination of the detector linearity, the limit of quantification, the accuracy of the method and the storage stability of sample final extracts.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 Ng/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L.
21 The occurrence of matrix effects was monitored. In all the sample materials, the measurement of phosphorous acid must be established using matrix matched standards. So the measurement of both compounds is established using matrix matched standards.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and 0.03 mg/kg of phosphorous acid.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of s 20% could be obtained.
The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so that this method modification has been validated successfully.
I Introduction Fosetyl-Al is a fungicide The method modification 00861/M001 presented in this report was validated in order to suppress the steps of clean up and derivatization, to change the analysis and detection modes
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and 0.03 mg/kg of phosphorous acid.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of s 20% could be obtained.
The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so that this method modification has been validated successfully.
I Introduction Fosetyl-Al is a fungicide The method modification 00861/M001 presented in this report was validated in order to suppress the steps of clean up and derivatization, to change the analysis and detection modes
22 and to decrease the Limit of Quantification (LOQ) of original method 00861 from 0.5 mg/kg to 0.01 mg/kg for fosetyl-Al and to 0.1 mg/kg for phosphorous acid.
Table 1: LOQ and principle of analytical determination Compound fosetyl-Al Phosphorous acid Determined as fosetyl-Al Phosphorous acid Calculated as fosetyl-Al Phosphorous acid Principle of Determination LC/MS/MS LC/MS/MS
LOQ' [mg/kg] Grape (whole fruit) 0.01 0.1 Orange (whole fruit) ........ ...................
_._...... 0.01 0.1 . .
............_........................._...__.._......._........................
.............. .........................
Lettuce (head) 0.01 0.1 ................. ....................
._........................................ .............
._......................................
Cucumber (whole fruit) 0.01 0.1 . ...... e.. ......_ ......................... .........
_......................................... _._..............
~... .....
Avocado (whole fruit) 0.01 0.1 ........... ........................ ..
........................._................................_....................
.......
Wheat (Grain> 0.01 0.1 i: defined as the lowest validated fortification level 1.1 Citation of the Original Method Original Method: 00861 Compounds : fosetyl-Al and its metabolite (phosphorous acid) Reason for Modification : = Suppress the steps of clean up and derivatization = Change analysis and detection modes from GC/FPD to LC/MS/MS
= Decrease the LOQ from 0.5 mg/kg to 0.010 mg/kg for fosetyl-Al and to 0.1 mg/kg for phosphorous acid 1.2 Physical and Chemical Properties Name of the Substance fosetyl-Al Substance Code AE F053616 Chemical Name Aluminium-tris-(ethylphosphonate) Empirical Formula C6 H18 Al O9P3 Structural Formula II
Aj CH3-CHZ_0'_i,0 3 H
Table 1: LOQ and principle of analytical determination Compound fosetyl-Al Phosphorous acid Determined as fosetyl-Al Phosphorous acid Calculated as fosetyl-Al Phosphorous acid Principle of Determination LC/MS/MS LC/MS/MS
LOQ' [mg/kg] Grape (whole fruit) 0.01 0.1 Orange (whole fruit) ........ ...................
_._...... 0.01 0.1 . .
............_........................._...__.._......._........................
.............. .........................
Lettuce (head) 0.01 0.1 ................. ....................
._........................................ .............
._......................................
Cucumber (whole fruit) 0.01 0.1 . ...... e.. ......_ ......................... .........
_......................................... _._..............
~... .....
Avocado (whole fruit) 0.01 0.1 ........... ........................ ..
........................._................................_....................
.......
Wheat (Grain> 0.01 0.1 i: defined as the lowest validated fortification level 1.1 Citation of the Original Method Original Method: 00861 Compounds : fosetyl-Al and its metabolite (phosphorous acid) Reason for Modification : = Suppress the steps of clean up and derivatization = Change analysis and detection modes from GC/FPD to LC/MS/MS
= Decrease the LOQ from 0.5 mg/kg to 0.010 mg/kg for fosetyl-Al and to 0.1 mg/kg for phosphorous acid 1.2 Physical and Chemical Properties Name of the Substance fosetyl-Al Substance Code AE F053616 Chemical Name Aluminium-tris-(ethylphosphonate) Empirical Formula C6 H18 Al O9P3 Structural Formula II
Aj CH3-CHZ_0'_i,0 3 H
23 Relative Molecular Mass 354.1 g/mol Monoisotopic Mass 354.0 g/mol Solubility Water 120 g/L (20 C) Acetonitrile 5 mg/L (20 C) Name of the Substance Phosphorous acid Substance Code AE 0540099 Chemical Name Phosphonic acid Empirical Formula H3PO3 Structural Formula 0 HO P OH
H
Relative Molecular Mass 82.0 g/mol Monoisotopic Mass 82.0 g/mol 2 Experimental Section 2.1 Materials 2.1.1 Apparatus = Standard laboratory glass equipment, rinsed with acetone.
= Balances :
- accuracy 0.1 mg (analytical standards) (e.g. Mettler AT261 range) - accuracy 0.1 g (samples) (e.g. Mettler PM6000) . Dilutor (e.g. Hamilton MicroLab 500) = High-speed blender (e.g. Ultra Turrax T25 with dispersion tool S 50 G-40G) (e.g. IKA) = Centrifuge (e.g. Hermle Z513K)
H
Relative Molecular Mass 82.0 g/mol Monoisotopic Mass 82.0 g/mol 2 Experimental Section 2.1 Materials 2.1.1 Apparatus = Standard laboratory glass equipment, rinsed with acetone.
= Balances :
- accuracy 0.1 mg (analytical standards) (e.g. Mettler AT261 range) - accuracy 0.1 g (samples) (e.g. Mettler PM6000) . Dilutor (e.g. Hamilton MicroLab 500) = High-speed blender (e.g. Ultra Turrax T25 with dispersion tool S 50 G-40G) (e.g. IKA) = Centrifuge (e.g. Hermle Z513K)
24 (ex Hettich EBA12) = HPLC (e.g. Binary Pump Agilent 1100) (e.g. Quaternary pump Agilent 1100) = Auto sampler (e.g. CTC Analytics HTC PAL) = Triple Quadrupole HPLC-MS/MS Mass Spectrometer (e.g. Sciex Instruments, API 4000 System) = Column (e.g. Hypercarb, 100 x 3.0 mm, 5 pm ) 2.1.2 Reagents and Supplies = Acetone, (e.g. SupraSolv Merck) = Acetonitrile, (e.g. SupraSolv Merck) = Methanol (e.g. SupraSolv Merck) = Formic acid (e.g. Normapur Prolabo) = PTFE filters (25mm, 0.45 pm), (e.g. Acrodisc CR Pall Gelman) = Polypro bottles (125 mL, wide opening) (e.g. Nalgen) = Conical centrifuge tube 15 mL (e.g. Merck 01 142.518) = Extraction solvent : Acetonitrile / water (50/50, v/v) = Solvent for dilution Methanol with 0.5 % HCOOH
= Mobile phase solvent: Water with 0.5 % HCOOH
2.1.3 Reference Item Only sufficiently characterised and certified item was used as reference item.
The reference item was made available by Bayer CropScience GmbH produkt Analytik, G864, Industriepark Hochst, D-65926 Frankfurt-am-Main, Germany.
Table 2: Reference item data Name of Substance Batch Number Content [%] Date of Expiry fosetyl-Al 12/1080 97.6 February 20, 2006 phosphorous acid 04911 DN 96.2 March 12, 2005 2.1.4 Standard Solutions Stock and standard solutions were stored protected from light in a refrigerator at around 5 C.
Stock solutions (1000 mg/L) Into a 100 mL amber screw-cap flask, weigh accurately between 20 and 50 mg of reference item. Using a burette, add a volume of water to obtain a stock solution of exactly 1000 mg/L. Mix thoroughly until complete dissolution using a magnetic stirrer. Two separate stock solutions must be prepared for each compound. After comparison of these two stock solutions, they are mixed.
Mixture solution First dilute 10 times fosetyl-Al stock solution with water. Then pipette 5 mL
of it and 5 mL of 5 phosphorous acid stock solution using a class "A+" pipette. Pour into a class "A+" 50 mL
volumetric flask. Adjust volume with water, cap and mix by shaking : Mixture solution (10 mg/L
fosetyl-Al - 100 mg/L phosphorous acid).
Fortifying standard solutions The mixture solution is also used as fortifying standard solution for recoveries at 10LOQ level.
10 Dilute it 10 times with water to obtain the fortifying standard solution used for recoveries at LOQ
level.
Standard solutions in solvent By appropriate dilution of the fortifying solution used for recoveries at LOQ
level (1 mg/L fosetyl-Al - 10 mg/L phosphorous acid), prepare the intermediate standard solution at 0.05 mg/L of 15 fosetyl-Al and 0.5 mg/L of phosphorous acid using methanol with 0.5% formic acid.
Standard solutions in solvent To obtain the standard solutions used for calibration, dilute extemporaneously using a dilutor and methanol with 0.5% formic acid, the intermediate standard solution to obtain the following 20 concentrations: 0.1 pg/L fosetyl-Al - 1 pg/L phosphorous acid, 0.2 pg/L
fosetyl-Al - 2 pg/L
phosphorous acid, 0.5 pg/L fosetyl-Al - 5 pg/L phosphorous acid, 1 pg/L
fosetyl-Al - 10 pg/L
phosphorous acid, 2 pg/L fosetyl-Al - 20 pg/L phosphorous acid and 5 pg/L
fosetyl-Al - 50 pg/L
phosphorous acid.
For wheat samples only, dilute extemporaneously using a dilutor and methanol with 0.5% formic
= Mobile phase solvent: Water with 0.5 % HCOOH
2.1.3 Reference Item Only sufficiently characterised and certified item was used as reference item.
The reference item was made available by Bayer CropScience GmbH produkt Analytik, G864, Industriepark Hochst, D-65926 Frankfurt-am-Main, Germany.
Table 2: Reference item data Name of Substance Batch Number Content [%] Date of Expiry fosetyl-Al 12/1080 97.6 February 20, 2006 phosphorous acid 04911 DN 96.2 March 12, 2005 2.1.4 Standard Solutions Stock and standard solutions were stored protected from light in a refrigerator at around 5 C.
Stock solutions (1000 mg/L) Into a 100 mL amber screw-cap flask, weigh accurately between 20 and 50 mg of reference item. Using a burette, add a volume of water to obtain a stock solution of exactly 1000 mg/L. Mix thoroughly until complete dissolution using a magnetic stirrer. Two separate stock solutions must be prepared for each compound. After comparison of these two stock solutions, they are mixed.
Mixture solution First dilute 10 times fosetyl-Al stock solution with water. Then pipette 5 mL
of it and 5 mL of 5 phosphorous acid stock solution using a class "A+" pipette. Pour into a class "A+" 50 mL
volumetric flask. Adjust volume with water, cap and mix by shaking : Mixture solution (10 mg/L
fosetyl-Al - 100 mg/L phosphorous acid).
Fortifying standard solutions The mixture solution is also used as fortifying standard solution for recoveries at 10LOQ level.
10 Dilute it 10 times with water to obtain the fortifying standard solution used for recoveries at LOQ
level.
Standard solutions in solvent By appropriate dilution of the fortifying solution used for recoveries at LOQ
level (1 mg/L fosetyl-Al - 10 mg/L phosphorous acid), prepare the intermediate standard solution at 0.05 mg/L of 15 fosetyl-Al and 0.5 mg/L of phosphorous acid using methanol with 0.5% formic acid.
Standard solutions in solvent To obtain the standard solutions used for calibration, dilute extemporaneously using a dilutor and methanol with 0.5% formic acid, the intermediate standard solution to obtain the following 20 concentrations: 0.1 pg/L fosetyl-Al - 1 pg/L phosphorous acid, 0.2 pg/L
fosetyl-Al - 2 pg/L
phosphorous acid, 0.5 pg/L fosetyl-Al - 5 pg/L phosphorous acid, 1 pg/L
fosetyl-Al - 10 pg/L
phosphorous acid, 2 pg/L fosetyl-Al - 20 pg/L phosphorous acid and 5 pg/L
fosetyl-Al - 50 pg/L
phosphorous acid.
For wheat samples only, dilute extemporaneously using a dilutor and methanol with 0.5% formic
25 acid, the intermediate standard solution to obtain the following concentrations : 0.31 tag/L
fosetyl-Al - 3.1 pg/L phosphorous acid, 0.5 pg/L fosetyl-Al - 5 pg/L
phosphorous acid, 0.83 pg/L
fosetyl-Al - 8.3 pg/L phosphorous acid, I pg/L fosetyl-Al - 10 pg/L
phosphorous acid, 2.5 pg/L
fosetyl-Al - 25 Ng/L phosphorous acid, 5 pg/L fosetyl-Al - 50 pg/L phosphorous acid and 8.3 pg/L fosetyl-Al - 83 pg/L phosphorous acid.
fosetyl-Al - 3.1 pg/L phosphorous acid, 0.5 pg/L fosetyl-Al - 5 pg/L
phosphorous acid, 0.83 pg/L
fosetyl-Al - 8.3 pg/L phosphorous acid, I pg/L fosetyl-Al - 10 pg/L
phosphorous acid, 2.5 pg/L
fosetyl-Al - 25 Ng/L phosphorous acid, 5 pg/L fosetyl-Al - 50 pg/L phosphorous acid and 8.3 pg/L fosetyl-Al - 83 pg/L phosphorous acid.
26 Matrix matched standard solutions used for calibration The occurrence of matrix effects was monitored. and the measurement of both compounds is established using matrix matched standards in all the sample materials.
From the intermediate standard solution, the dilutions are the same as preparation of standard solutions in solvent, except the dilution mixture which is the final extract of a control sample.
Remark : 20 to 25 mL of final extract are necessary to make all dilutions. If the step of filtration is difficult, several filters can be used.
2.1.5 Stability of the standard solutions The stock solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 4 months and a half.
The fortifying standard solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 2 months and a half.
2.2 Residue Analytical Methodology Some modifications compared to the original analytical method were introduced :
The method modification 00861/M001 presented in this report was validated in order to suppress the steps of clean up and derivatization, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00861 from 0.5 mg/kg to 0.01 mg/kg for fosetyl-Al and to 0.1 mg/kg for phosphorous acid.
= The Limit of Quantification was decreased from 0.5 mg/kg to 0.01 mg/kg for fosetyl-Al and to 0.1 mg/kg for phosphorous acid.
= The C18 SPE cartridge clean-up step was suppressed.
= The derivatization step was suppressed.
= The quantification was carried out by LC/MS/MS instead of GC/FPD.
All modifications were included in the description below.
A flow chart of the method is given in Appendix 1.
For recovery experiments, samples are fortified by adding the appropriate standard solution to the sample material after weighing and before extraction.
Extraction 1. Weigh 20.0 g of homogeneous sample material into a 125 mL polypropylene bottle.
Note: weight of the sample is used for residue calculation, addressed as variable G
2. Add 80 mL of acetonitrile / water (50/50, v/v).
From the intermediate standard solution, the dilutions are the same as preparation of standard solutions in solvent, except the dilution mixture which is the final extract of a control sample.
Remark : 20 to 25 mL of final extract are necessary to make all dilutions. If the step of filtration is difficult, several filters can be used.
2.1.5 Stability of the standard solutions The stock solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 4 months and a half.
The fortifying standard solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 2 months and a half.
2.2 Residue Analytical Methodology Some modifications compared to the original analytical method were introduced :
The method modification 00861/M001 presented in this report was validated in order to suppress the steps of clean up and derivatization, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00861 from 0.5 mg/kg to 0.01 mg/kg for fosetyl-Al and to 0.1 mg/kg for phosphorous acid.
= The Limit of Quantification was decreased from 0.5 mg/kg to 0.01 mg/kg for fosetyl-Al and to 0.1 mg/kg for phosphorous acid.
= The C18 SPE cartridge clean-up step was suppressed.
= The derivatization step was suppressed.
= The quantification was carried out by LC/MS/MS instead of GC/FPD.
All modifications were included in the description below.
A flow chart of the method is given in Appendix 1.
For recovery experiments, samples are fortified by adding the appropriate standard solution to the sample material after weighing and before extraction.
Extraction 1. Weigh 20.0 g of homogeneous sample material into a 125 mL polypropylene bottle.
Note: weight of the sample is used for residue calculation, addressed as variable G
2. Add 80 mL of acetonitrile / water (50/50, v/v).
27 3. Blend the sample using a high-speed blender (IKA or equivalent) for approx.
5 minutes.
4. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
5. Pour the supernatant into a 200 mL volumetric flask.
6. Add 80 mL of acetonitrile / water (50/50, v/v) on the bottom.
7. Blend the sample using a high-speed blender (IKA or equivalent) for approx.
5 minutes.
8. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
9. Pour the supernatant into the volumetric flask.
10. Make-up to 200 mL with methanol. This is the Extract A.
Note: volume of extract A is used for residue calculation, addressed as variable V
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. Filter the supernatant through an Acrodisc CR 25 mm PTFE filter (0.45 pm).
13. Dilute five times the extract using acidified methanol with formic acid 0.5 %. This is the Final Extract.
14. Proceed to LC/MS/MS measurement, Chapter 2.3.
Remark : for wheat samples, from stage 10, follow the preparation as described below :
10. Add 1 mL of concentrated formic acid and make-up to 200 mL with methanol.
This is the Extract A.
Note: volume of extract A is used for residue calculation, addressed as variable V
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. With dilutor, dilute twice the supernatant using methanol with formic acid 0.5%.
13. Filter the extract through an Acrodisc CR 25 mm PTFE filter (0.45 pm).
This is the Final Extract.
14. Proceed to LC/MS/MS measurement, Chapter 2.3.
2.3 Analysis and Instrument Conditions The final extracts are injected into a high performance liquid chromatograph and detected by tandem mass spectrometry with electrospray ionisation.
The quantification is carried out by external standardisation using matrix matched standards.
Exemplary LC/MS/MS conditions that were used in the course of this method validation are listed in chapters 2.3.1 and 2.3.2. These conditions are given as a guidance and may have to be adapted for other HPLC-MS/MS systems.
2.3.1 HPLC Conditions Instrument: Binary pump Agilent 1100 Quaternary pump Agilent 1100 (make-up solvent) Auto sampler: CTC Analytics HTC PAL
5 minutes.
4. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
5. Pour the supernatant into a 200 mL volumetric flask.
6. Add 80 mL of acetonitrile / water (50/50, v/v) on the bottom.
7. Blend the sample using a high-speed blender (IKA or equivalent) for approx.
5 minutes.
8. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
9. Pour the supernatant into the volumetric flask.
10. Make-up to 200 mL with methanol. This is the Extract A.
Note: volume of extract A is used for residue calculation, addressed as variable V
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. Filter the supernatant through an Acrodisc CR 25 mm PTFE filter (0.45 pm).
13. Dilute five times the extract using acidified methanol with formic acid 0.5 %. This is the Final Extract.
14. Proceed to LC/MS/MS measurement, Chapter 2.3.
Remark : for wheat samples, from stage 10, follow the preparation as described below :
10. Add 1 mL of concentrated formic acid and make-up to 200 mL with methanol.
This is the Extract A.
Note: volume of extract A is used for residue calculation, addressed as variable V
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. With dilutor, dilute twice the supernatant using methanol with formic acid 0.5%.
13. Filter the extract through an Acrodisc CR 25 mm PTFE filter (0.45 pm).
This is the Final Extract.
14. Proceed to LC/MS/MS measurement, Chapter 2.3.
2.3 Analysis and Instrument Conditions The final extracts are injected into a high performance liquid chromatograph and detected by tandem mass spectrometry with electrospray ionisation.
The quantification is carried out by external standardisation using matrix matched standards.
Exemplary LC/MS/MS conditions that were used in the course of this method validation are listed in chapters 2.3.1 and 2.3.2. These conditions are given as a guidance and may have to be adapted for other HPLC-MS/MS systems.
2.3.1 HPLC Conditions Instrument: Binary pump Agilent 1100 Quaternary pump Agilent 1100 (make-up solvent) Auto sampler: CTC Analytics HTC PAL
28 Column: Hypercarb, 100 x 3.0 mm, 5 pm Precolumn: Phenomenex C18 ODS, 4 x 2.0mm Injection Volume: 20 pL
Column temperature: ambient (about 25 C) Mobile Phase: Isocratic mode: 35 / 65 (v/v) Methanol / water + 0.5% formic acid Flow (Column): 400 pL/min Retention Times: from 4 to 6 min for phosphorous acid and from 7 to 10 min for fosetyl-Al.
Divert valve: Valve situated between the analytical column and the MS/MS
system.
This valve was used to protect the ion source from contamination and to reduce the risk of ion suppression occurring, the eluent from the first minutes of the run was diverted to waste and a make-up flow was used to obviate the need for the ion source to stabilize after diverting the LC
eluent flow back to the mass spectrometer.
Make up solvent: 50/50 (v/v) Methanol / water Divert flow: 200 pL/min Remarks :
= It is necessary to wait about 2 hours the stabilisation of the HPLC system before injecting.
During a samples set, a light drift of retention time of both compounds can be observed.
= Hypercarb precolumn must not be used.
2.3.2 MS/MS Conditions The experiments were performed on a triple-quadrupole mass spectrometer system, fitted with an electrospray interface operated in the negative ion mode under MRM
(multiple reaction monitoring) conditions.
For instance:
Detector: Triple Quadrupole HPLC-MS/MS Mass Spectrometer, e.g. Sciex Instruments, API 4000 System Source: TIS (Turbo Ion Spray) Temperature: 600 C
Scan Type: MRM-Mode (Multiple Reaction Monitoring Mode)
Column temperature: ambient (about 25 C) Mobile Phase: Isocratic mode: 35 / 65 (v/v) Methanol / water + 0.5% formic acid Flow (Column): 400 pL/min Retention Times: from 4 to 6 min for phosphorous acid and from 7 to 10 min for fosetyl-Al.
Divert valve: Valve situated between the analytical column and the MS/MS
system.
This valve was used to protect the ion source from contamination and to reduce the risk of ion suppression occurring, the eluent from the first minutes of the run was diverted to waste and a make-up flow was used to obviate the need for the ion source to stabilize after diverting the LC
eluent flow back to the mass spectrometer.
Make up solvent: 50/50 (v/v) Methanol / water Divert flow: 200 pL/min Remarks :
= It is necessary to wait about 2 hours the stabilisation of the HPLC system before injecting.
During a samples set, a light drift of retention time of both compounds can be observed.
= Hypercarb precolumn must not be used.
2.3.2 MS/MS Conditions The experiments were performed on a triple-quadrupole mass spectrometer system, fitted with an electrospray interface operated in the negative ion mode under MRM
(multiple reaction monitoring) conditions.
For instance:
Detector: Triple Quadrupole HPLC-MS/MS Mass Spectrometer, e.g. Sciex Instruments, API 4000 System Source: TIS (Turbo Ion Spray) Temperature: 600 C
Scan Type: MRM-Mode (Multiple Reaction Monitoring Mode)
29 Polarity: Negative ion mode Gas Flows: Nebulization Gas Air (GS1):40 Turbo Gas Air (GS2): 60 Curtain Gas N2 (CUR): 20 Collision Gas N2 (CAD): 6Collision Energy:
Compound Precursor Ion Product Ion Dwell Time Collision Energy Q1 Mass (amu) Q3 Mass (amu) (msec) (V) fosetyf-AI 109.0 80.9 200 -38 Phosphorous acid 80.9 62.9 600 -16 Table 3: Mass spectrometer scan parameters for the quantifier ions used. The detailed instrument settings used are given in chapters 2.3.1 and 2.3.2. Varying instrument systems or instrument parameters may result in different ion transitions and different relative intensities.
Note: Some mass spectrometer conditions are instrument specific. The spectrometer conditions should be optimised by a competent operator prior to analysis.
Details on MS/MS and LC conditions are given in Appendix 2.
The fragmentation pathways for the quantifier ions for fosetyl-Al and phosphorous acid are shown in Figure 1 and in Figure 2.
Figure 1: Proposed fragmentation pathway for fosetyl-Al.
0 I - loss of C2H4 0 I
H3C-H-p-p-O Hp-P-p ' m/z 109 m/z 81 Figure 2: Proposed fragmentation pathway for phosphorous acid.
0 - loss of H20 -H
m/z 81 m/z 63 2.3.3 Confirmatory transitions 5 To confirm or exclude some interference or pollution in samples, the following transitions can be used in the same conditions described above :
Compound Precursor Ion Product Ion Dwell Time Collision Energy (V) Q1 Mass (amu) Q3 Mass (amu) (msec) fosetyl-Al 109 63 200 -38 phosphorous acid 80.9 78.9 600 -22 The fragmentation pathways for the confirmatory transitions for fosetyl-Al and phosphorous acid 10 are shown in Figure 3 and in Figure 4.
Figure 3: Proposed fragmentation pathway for fosetyl-Al I I - loss of C2H4 -O
H2 H and H20 m/z 109 m/z 63 Figure 4: Proposed fragmentation pathway for phosphorous acid II - loss of H2 -H
15 m/z81 m/z79 Note : all recovery samples were also analysed using confirmatory transitions.
The results are given in Appendix 3.
2.4 Linearity of the Detector The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L.
Table 4: Standard concentrations prepared for the determination of detector linearity. The concentration corresponding to the LOQ is given in the second column of the table.
HPLC-MS/MS Standard Concentrations [Ng/L]
fosetyl-Al 0.1 0.2 0.5 1 2 5 phosphorous acid Table 5: Standard concentrations used for wheat samples and prepared for the determination of detector linearity. The concentration corresponding to the LOQ is given in the second column of the table.
HPLC-MS/MS Standard Concentrations [pg/L]
fosetyl-Al 031 0.5 0.83 1 2.5 5 8.3 phosphorous 3.1 5 8.3 10 25 50 83 acid 2.5 Storage Stability of Extracts The stability of sample extracts containing fosetyl-Al and phosphorous acid was determined for each sample material.
For this purpose, the final extract of recovery samples were stored in the auto sampler rack thermo stated at about 10 C after initial analysis and re-analysed after a storage period of several days.
2.6 Calculation 2.6.1 Calculation of Residues Evaluation in this case is performed according to the external standardisation using matrix matched standards.
During the analysis of each set of samples, the 6 (or 7 for wheat samples) standard solutions mentioned in Table 4 are injected once. Standards should be interspersed with samples to compensate for any minor change in instrument response.
For each compound, the peak area is plotted versus the concentration in order to establish a calibration curve obtained by linear regression weighting 1/x with least squares method.
The corresponding model to determine the concentration in final extracts is calculated using the Analyst Software (Version 1.4).
Each final extract is injected once using the same conditions as previously described for the standard solutions.
Using the predicting mathematical model previously established, the final concentration in Ng/L
of each compound is determined for each injection.
For each compound, the amount of residue R, expressed in mg/kg is calculated, using the following formula :
R= CxVxD
1000x C7 where: R : Determined amount of residue of fosetyl-Al or phosphorous acid in mg/kg C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in pg/L
V : Volume of the extract A in mL, here 200 mL
D : Dilution factor to obtain the Final Extract, here 5 (or 2 for wheat samples) G : Sample weight of analytical sample in g, here 20 g 2.6.2 Calculation of Recovery Rates The concentration of each compound in pg/L is determined for the recovery sample according to 2.6.1.
The percent recovery rate is then calculated as folfows :
CX1oo Rec =
A
where: Rec : Recovered amount found in fortified sample in %
C : Concentration of fosetylAl or phosphorous acid found in the analysed extract in pg/L
A : Fortified amount of fosetyl-Al or phosphorous acid in pg/L
2.6.3 Calculation of Relative Standard Deviation (RSD) The RSD is calculated as follows :
RSD (%) = S.D. / Mean Recovery x 100 %
E (R; - Rm)2 R; : recovery S.D. = [ 1 1iz Rm : mean recovery n-1 n : number of recoveries 3 Results and Discussion 3.1 Specificity and Selectivity The method allows the determination of fosetyl-Al and its metabolite (phosphorous acid) in/on grape, orange, lettuce, cucumber, avocado and wheat samples.
The specificity of the method resulted from the HPLC separation in combination with the very selective MS/MS detection.
3.2 Apparent residues in Control Samples Two control samples were analysed for each sample material. The origin of the control materials used is listed in Table 6.
Table 6: Origin of untreated control samples Sample Material Origin Grape (whole fruit) Mr Lusson - Angers - France Orange (whole fruit) Market specialised in organic food - France Lettuce (head) Market specialised in organic food - France Cucumber (whole fruit) Market specialised in organic food - France Avocado (whole fruit) Control sample from Bayer CropScience - Monheim -Germany Wheat (Grain) Control sample from Bayer CropScience - Monheim - Germany A residue level estimation in control samples was performed. The results are listed in Table 7.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and < 0.03 mg/kg of phosphorous acid.
Table 7: Apparent residues in untreated control samples for fosetyl-Al and phosphorous acid Sample Control Sample LOQ Apparent residues Material [mg/kg] [mg/kg]
fosetyl-AI phospho- fosetyl-Al phospho-rous acid rous acid Grape (whole Mr Lusson - Angers - 0.01 0.1 < 0.003 < 0.03 fruit) FRANCE
Orange Market specialised in organic 0.01 0.1 < 0.003 < 0.03 (whole fruit) food - France Lettuce Market specialised in organic 0.01 0.1 < 0.003 < 0.03 (head) food - France Cucumber Market specialised in organic 0.01 0.1 < 0.003 < 0.03 (whole fruit) food - France Avocado Control sample from Bayer (whole fruit) CropScience - Monheim - 0.01 0.1 < 0.003 < 0.03 Germany Wheat (Grain) Control sample from Bayer CropScience - Monheim - 0.01 0.1 < 0.003 < 0.03 Germany 3.3 Linearity of the Detectors and Matrix Effects The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
5 The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 Ng/L and I and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L.
Experimental details can be found in Chapter 2.4.
In each chromatogram, the measured peak area of fosetyl-Al or phosphorous acid is plotted 10 versus the corresponding concentration of respectively fosetyl-Al or phosphorous acid contained in each standard solution, in order to obtain calibration curve of the form y = ax+b (1/xweighting) where : y = peak area, x = concentration in injected standard solution 15 The results of the determination of detector response for LC/MS/MS are summarised in Table 8.
Table 8: Summary of the determination of detector linearity for LC/MS/MS.
phosphorous Detection Parameter fosetyl-Al acid LC/MS/MS Linear range [pg/Lj 0.1 - 5 1- 50 (or 0.31 - 8.3 for (or 3.1 - 83 for wheat) wheat) ............... .W........................ ................................
.._ ......_._........m.............................................................
No. of concentrations 6 6 (or 7 for wheat) (or 7 for wheat) No. of injections 1 1 Model 1/x weighted 1/x weighted linear regression linear regression Correlation coefficient (R) > 0.9990 > 0.9900 for standards prepared in solvent Correlation coefficient (R) > 0.9990 > 0.9985 for matrix matched standards An excellent linear correlation between the injected amount of the analytes and the detector responses of LC/MS/MS was observed for standards in the range of 0.1 to 5 pg/L
(or 0.31 to 8.3 pg/L for wheat) for fosetyl-Al and in the range of 1 to 50 pg/L (or 3.1 to 83 pg/L for wheat) for phosphorous acid, using either standards prepared in solvent or matrix matched standards.
The occurrence of matrix effects was monitored. The results are shown in Table 9 and table 10.
Table 9: Matrix effect evaluation for fosetyl-Al FL: Fortification Level Measurement using Number Sampfe Material FL of Values Standards in pure Matrix matched [mg/kg] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
Grape (whole fruit) 0.01 5 100 3.1 100 2.9 0.10 5 102 0.9 101 0.9 Orange (whole fruit) 0.01 5 90 6.3 97 6.0 0.10 5 90 4.6 92 4.5 Lettuce (head) 0.01 5 108 6.1 108 6.2 0.10 5 105 1.7 105 2.1 Cucumber (whole fruit) 0.01 5 97 2.1 96 1.6 0.10 5 98 2.3 101 2.7 Avocado (whole fruit) 0.01 5 99 4.9 96 5.0 0.10 5 87 1.9 87 1.9 Wheat (Grain) 0.01 5 87 5.5 88 5.4 0.10 5 74 5.3 73 5.5 Tabie 10: Matrix effect evaluation for phosphorous acid FL: Fortification Level Measurement using Number Sample Material FL of Values Standards in pure Matrix matched [mg/kg] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
0.1 5 156 6.7 99 8.5 Grape (whole fruit) 1 5 131 1.9 102 2.1 Orange (whole fruit) 0.1 5 189 10.6 76 18.3 1 5 147 2.5 98 2.3 Lettuce (head) 0.1 5 193 6.4 81 9.7 1 5 160 3.8 104 3.9 Cucumber (whole fruit) 0.1 5 185 4.7 87 7.0 1 5 135 2.6 100 2.2 Avocado (whole fruit) 0.1 5 139 3.7 73 5.1 1 5 132 6.8 100 6.7 Wheat (Grain) 0.1 5 152 8.3 98 5.8 1 5 163 2.6 79 2.5 In all the sample materials, the measurement of phosphorous acid must be established using matrix matched standards. So the measurement of both compounds is established using matrix matched standards.
3.4 Limit of Quantification and Recovery Experiments The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of <_ 20% could be obtained. The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), fettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
To validate the method for these matrices, samples were fortified with a defined amount of fosetyl-Al and phosphorous acid prior to analysis.
3.5 Recovery Rates The detailed recovery results obtained are listed in Table 11 and Table 12.
Table 11: Recovery rates obtained for fosetyl-Al, FL: fortification level, RSD: relative standard deviation FL Recovery of fosetyl-Al Crop Sample Material [m9/kg] Single Values [%] Mean [%] RSD [%]
Grape Whole fruit 0.01 102 102 95 100 2.9 .......... .................... _............... ......
........................ .... _................. ................
_...................................... ... ..................... ......
............ ....................... _...... .......... _...................
_..........
0.1 101 102 102 101 0.9 Overall Mean and RSD 101 2.1 Orange Whole fruit 0.01 102 100 98 97 6.0 ...................................... _..... ........ .. ..............
....................
....._....__................................................... _............
_.._................ ................. _........................... ........
................ ...... _._.......
0.1 96 95 94 92 4.5 Overall Mean and RSD 95 5.6 Lettuce Head 0.01 104 98 109 108 6.2 ...... ................. ........ ............... ..... _.................
__......... _..._......... .................................................
...._.._......... .._............................. ........... .....
_......................... _..........
0.1 102 106 104 105 2.1 Overall Mean and RSD 106 4.5 Cucumber Whole fruit 0.01 95 96 98 96 1.6 0.1 106 101 101 101 2.7 Overall Mean and RSD 99 3.4 Avocado Whole fruit 0.01 104 95 92 96 5.0 ................ ............... ........
.........................................................
_........................................................
.............................................. ..............
_........................ _....
0.1 88 88 85 87 1.9 Overall Mean and RSD 91 6.1 Wheat Grain 0.01 86 92 93 88 5.4 _..... . ........................................
................................................................ .........
._..................... _........................... _.......... .......
_............ ......................... ..._. . .
...................................
0.1 75 79 69 73 5.5 Overall Mean and RSD 80 10.9 Table 12: Recovery rates obtained for Phosphorous acid, FL: fortification level, RSD: relative standard deviation FL Recovery of Phosphorous acid Crop Sample Material [mg/kg] Single Values [%] Mean [%] RSD [%]
Grape Whole fruit 0.1 96 94 113 99 8.5 ...................................................... ....................
........................................................................._.....
..............,.......__....... ............ _...... ........ _..............
..............................................
1 100 105 104 102 2.1 Overall Mean and RSD 101 6.0 Orange Whole fruit 0.1 65 99 70 76 18.3 1 97 99 101 98 2.3 Overall Mean and RSD 87 17.3 Lettuce Head 0.1 82 94 76 81 9.7 ..... _ ............................................. ....... __.......
.__........................................ _.._.........
_.................................... .... ..........
.......................... ............. _.....
................................... _.........
1 103 108 98 104 3.9 Overall Mean and RSD 93 14.7 Cucumber Whole fruit 0.1 83 82 82 87 7.0 1 102 102 101 100 2.2 Overall Mean and RSD 93 8.9 Avocado Whole fruit 0.1 74 77 68 73 5.1 1 110 97 92 100 6.7 Overall Mean and RSD 87 17.8 Wheat Grain 0.1 90 94 101 98 5.8 .. ............................ _.._.. ....... . ..............
........................... _...................... _.__........
........................................................
....................... ............ _.........
.................................... __......
1 77 77 81 79 2.5 Overall Mean and RSD 89 12.2 The obtained recovery rates are summarised below in Table 13.
In total 60 recovery rates were determined for each compound. The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60).
Table 13: Summary of the recovery data for the determination of accuracy and repeatability;
RSD: relative standard deviation Parameter Phospho-rous rous acid Accuracy Single recoveries [%] 69 - 114 65 - 113 Mean recoveries per fortification level [%] 93 - 97 86 - 97 Mean recoveries per sample material [%] 80 - 106 87 - 101 Overall mean [%] 95 91 Number of values n 60 60 Repeatability RSD per fortification level [%] 7.6 - 12.3 9.5 -14.9 RSD per sample material [%] 2.1 - 10.9 6.0-17.8 Overall RSD [%] 10.2 13.7 3.6 Storage Stability of Extracts The stability of final extracts containing fosetyl-Al and its metabolite phosphorous acid was determined. For this purpose, the final extracts of recovery samples were let in the auto sampler rack thermo stated at about 10 C after initial analysis and re-analysed after a storage period of several days.
The results of the storage stabilities are detailed in Table 14.
Table 14: Stability period of final extracts in the auto sampler rack at about Sample Material Stability period (days) Grape (whole fruit) 7 days Orange (whole fruit) 4 days Lettuce (head) 8 days Cucumber (whole fruit) 8 days Avocado (whole fruit) 4 days Wheat (Grain) 3 days 4 Evaluation and Discussion The presented residue analytical method modification 00861/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit),avocado (whole fruit), and wheat (grain) by LC/MS/MS.
fosetyl-Al and its metabolite (phosphorous acid) were extracted from the sample material with a mixture of acetonitrile/water (50/50). After centrifugation and dilution of the sample material, the residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation in matrix matched standards The validation set included the determination of the detector linearity, the limit of quantification, the accuracy of the method and the storage stability of sample final extracts.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L. The detector response was linear in these ranges.
The occurrence of matrix effects was monitored.
In all the sample materials, the measurement of phosphorous acid must be established using matrix matched standards. So the measurement of both compounds is established using matrix matched standards.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and < 0.03 mg/kg of phosphorous acid.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of <_ 20% could be obtained. The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so that this method modification has been validated successfully.
Appendix 1 Flow Diagram of Residue Method 00861/M001 Extraction 1. Weigh 20.0 g of homogeneous sample material into a 125 mL polypropylene bottle.
2. Add 80 mL of acetonitrile / water (50/50, v/v).
3. Blend the sample using a high-speed blender (IKA or equivalent) for approx. 5 minutes.
4. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
5. Pour the supernatant into a 200 mL volumetric flask.
6. Add 80 mL of acetonitrile / water (50/50, v/v) on the bottom.
7. Blend the sample using a high-speed blender (IKA or equivalent) for approx. 5 minutes.
8. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
9. Pour the supernatant into the volumetric flask.
10. Make-up to 200 mL with methanol. This is the Extract A.
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. Filter the extract through an Acrodisc CR 25 mm PTFE filter (0.45 pm).
13. Dilute five times the extract using acidified methanol with formic acid 0.5 %. This is the Final Extract.
Remark : for wheat samples, from stage 10, follow the preparation as described below :
10. Add 1 mL of concentrated formic acid and make-up to 200 mL with methanol. This is the Extract A.
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. With dilutor, dilute twice the supernatant using acidified methanol with formic acid 0.5 %.
13. Filter the extract through an Acrodisc CR 25 mm PTFE filter (0.45 pm). This is the Final Extract.
HPLC Measurement with Electrospray MS/MS detection Appendix 2 Details on LC-MS/MS conditions Comment:
Synchronization Mode: LC Sync Auto-Equilibration: Off Acquisition Duration: 11 min59sec Number Of Scans: 888 Periods In File: 1 Acquisition Module: Acquisition Method Software version Analyst 1.4 MS Method Properties:
Period 1:
--------------Scans in Period: 888 Relative Start Time: 0.00 msec Experiments in Period: 1 Period 1 Experiment 1:
----------------------------Scan Type: MRM (MRM) Polarity: Negative Scan Mode: N/A
Ion Source: Turbo Spray Resolution Q1: Unit Resolution Q3: Unit Intensity Thres.:0.00 cps Settling Time: 0.0000 msec MR Pause: 5.0070 msec MCA: No Step Size: 0.00 amu Quantifier transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 62.90 600.00 DP -55.00 -55.00 (phosphorous acid) CE -38.00 -38.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 109.00 80.90 200.00 DP -45.00 -45.00 (fosetyl-AI) CE -16.00 -16.00 Parameter Table (Period 1 Experiment 1):
CUR: 20.00 GS1: 40.00 GS2: 60.00 IS: -4500.00 TEM: 600.00 ihe: ON
CAD: 6.00 EP -10.00 CXP -1.00 Confirmatory transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 78.90 600.00 DP -55.00 -55.00 (phosphorous acid) CE -22.00 -22.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 109.00 63.00 200.00 DP -45.00 -45.00 (fosetyl-Al) CE -38.00 -38.00 Parameter Table (Period 1 Experiment 1):
CUR: 20.00 GS1: 40.00 GS2: 60.00 IS: -4500.00 TEM: 600.00 ihe: ON
CAD: 6.00 EP -10.00 CXP -5.00 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Binary Pump Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Dead Volume (pl): 40.0 Maximum Flow Ramp (ml/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 Step Table:
Step Total Time(min) Flow Rate(pl/min) A(%) B(%) 0 0.00 400 65.0 35.0 1 10.00 400 65.0 35.0 Left Compressibility: 50.0 Right Compressibility: 115.0 Left Dead Volume (pl): 40.0 Right Dead Volume (pl):40.0 Left Stroke Volume (pl): -1.0 Right Stroke Volume (NI): -1.0 Left Solvent: A2 (water + 0.5% formic acid) Right Solvent: B2 (methanol) CTC PAL Auto sampler Method Properties :
Loop Volumel (pl): 100 Loop Volume2 (pI): 20 Injection Volume (pI): 50.000 Method Description:
Syringe: 250u1 Analyst LC-Inj Air Volume (pI) 0 Pre Clean with Solvent 1O 2 Pre Clean with Solvent 2() 1 Pre Clean with Sample () 0 Filling Speed (NI/s) 50 Filling Strokes () 0 Inject to LC VIv2 Injection Speed (pUs) 50 Pre Inject Delay (ms) 500 Post Inject Delay (ms) 500 Post Clean with Solvent 1() 3 Post Clean with Solvent 2() 2 Valve Clean with Solvent 1() 2 Valve Clean with Solvent 2() 1 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Quaternary Pump Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Compressibility: 100.0 Dead Volume (pI): 40.0 Stroke Volume (NI): -1.0 Maximum Flow Ramp (ml/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 Step Table:
Step Total Time Flow Rate A(%) B(%) C( /o) D(%) TE#1 TE#2 TE#3 TE#4 (min) (taUmin) (water) (methanol) 0 0.00 200 50.0 50.0 0.0 0.0 open open open open 1 10.00 200 50.0 50.0 0.0 0.0 open open open open Primary Flow Rate (ul/min): 200.0 Flow Sensor Calibration Table Index: 0 Valco Valve Method Properties Valco Valve Diverter Total Time (min) Position 1 0.0 B waste 2 3.0 A spectro Gas pressure Auto sampler CTC Analytics HTS Pal n 1303 N2 4 bar Peltier rack 10 C
Air gas 7.5 bar Loop 20 pL
Air Exhaust gas 4 bar Solvent 1 H20 + 0.5 % HCOOH
Solvent 2 MeOH
Oven Agilent G1316A n 1294 Tem erature Not used Valco valve Column selector n 1289 n 1290) Ten ports 6 positions 2 positions Not used A = MS B = Waste Pumps Source Probe TurbolonSpray n 1291 Binary pump Agilent 1100 G1312A 133 bar n 1288 n 1297) Flow 0.4 mL/min Horizontal Position 7 (x axis) A2 = H20+ 0.5% Formic Acid 65 % Vertical Position 7 axis) B2=MeOH 35%
Ca illa exit 1 mm Isocratic Mass Spectrometer API 4000 Device GLP n 1292 Quaternary pump Agilent 1100 G1354A n 1298 Flow 0.2mL/min Column A = H20 50 % Precolumn SMPREA1 B = MeOH 50 % Column SMAR 69-1 C = - Thermo Hypercarb 100 x 3.0mm 5 m D = - (ambient tem erature lsocratic mode Appendix 3 Results obtained with confirmatory transitions FL Recovery of fosetyl-Al Crop Sample Material [mg/kg] Single Values [%] Mean [%] RSD [%]
Grape Whole fruit 0.01 101 107 106 100 8.8 0.1 98 102 93 99 4.5 Overall Mean and RSD 99 6.7 Orange Whole fruit 0.01 121 121 110 110 10.3 ..... ..... ................ _............. _.......
........................................................ ...........
_......... ........ . ...........................................
_............ .__._.._.._.................. ............... ..... _.....
_..... ........ _ 0.1 98 102 91 94 7.0 Overall Mean and RSD 102 12.2 Lettuce Head 0.01 113 102 90 97 10.9 .................. _... _............ .. _..... .....
_........................... _........ _..... .
..................................................... _ _..............
.................................... _....... .......................
_............. _.....
0.1 95 97 96 96 1.4 Overall Mean and RSD 97 7.4 Cucumber Whole fruit 0.01 117 117 107 110 6.0 0.1 100 100 102 100 1.4 Overall Mean and RSD 105 6.6 Avocado Whole fruit 0.01 93 94 91 92 4.9 0.1 85 87 85 85 1.4 Overall Mean and RSD 89 5.4 Wheat Grain 0.01 83 88 98 89 7.3 ............. -_................................... .........................
................ _..._-.............. ..................................... .
_................... ......... ........... ......... _.... __....... .........
.. .... _........................... _........
0.1 72 81 73 75 5.2 Overall Mean and RSD 81 10.8 Grape Whole fruit 0.1 91 86 119 96 14.1 ............................................. ................... .........
..._._............ . .......................................................
_............... _.............. _.......................... _.... ..........
.................... ...........................
1 99 101 98 100 1.6 Overall Mean and RSD 98 9.6 Orange Whole fruit 0.1 69 92 68 74 14.1 .................................. _................ ........
_................... ..... . ........................... _........
_........... ........................................ _........... ........
_.....................................
..............................................
1 108 106 106 104 4.3 Overall Mean and RSD 89 19.8 Lettuce Head 0.1 91 80 94 81 14.3 ......... .................. ..._.....
...............................................................................
....... ..................... ....................... _.....
....................... _.. .... ....... ..._.... _........... .__.......
_......
1 103 105 101 102 2.0 Overall Mean and RSD 91 14.9 Cucumber Whole fruit 0.1 90 93 77 86 9.9 ................................. . ........... ............................
_.... .............. . ........... .
................................................. _ _.....................
................ ......................... ............... _.. _...........
_...........
1 101 100 101 99 2.5 Overall Mean and RSD 93 9.8 Avocado Whole fruit 0.1 71 81 84 76 8.0 1 113 107 103 104 5.5 Overall Mean and RSD 90 17.5 Wheat Grain 0.1 74 74 77 74 2.9 ......................................... _........... ..__.....
........................... _. ........ ........... __...................
_.............. ........... . .................. ........
_.................... ................ .........._............................
....
1 75 82 78 80 4.0 Overall Mean and RSD 77 5.1 FL : Fortification Level Example 4:
This detailed example concerns the analysis of fosetyl-Al and of phosphorous acid using water samples. This example is a modification M001 to the Analytical Method 00931 for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in/on drinking water and surface water by LCMSMS.
The presented residue analytical method modification 00931/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in drinking water and surface water by LC/MS/MS.
The sample material is treated with a cationic resin and then concentrated.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation.
The quantification was done by an external standardisation in matrix matched standards.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.2 and 20 pg/L.
The occurrence of matrix effects was monitored. In drinking water, the measurement of fosetyl-Al must be established using matrix matched standards. The results obtained with standards in pure solvent for phosphorous acid in both sample materials do not always comply with European requirements. So the measurement of both compounds in drinking water and surface water is established using matrix matched standards.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.00003 mg/L.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of 20% could be obtained.
The LOQ was set at 0.0001 mg/L for each compounds in drinking water and surface water.
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 75 to 118 % for fosetyl-Al and of 72 to 117 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 89 to 96 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 93% and of 91 to 93 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 92 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
The relative standard deviations (RSD) for the single fortification levels ranged from 9.6 to 14.3 % for fosetyl-Al and from 8.8 to 19.8 % for phosphorous acid (n=10).
The overall RSD values per sample material were between 7.5 and 9.7 % for fosetyl-Al and 9.3 and 12.4 % for phosphorous acid (n=10). The RSD value across all samples was 12.7 % for fosetyl-Al and 15.0 % for phosphorous acid (n=20). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so this method modification has been validated successfully.
A variant method was also validated on drinking water and surface water. The sample preparation of the main method was strongly simplified by the suppression of the concentration step. The variant method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996), for non concentrated drinking water and surface water at 0.1 Ng/L
for fosetyl-Al and ten times this limit for fosetyl-Al and at 1 pg/L for phosphorous acid when matrix matched standards were used, independently of the LC conditions tested.
Regarding to the main method, the sample preparation was greatly simplified and allows to save a lot of time.
1. Introduction Fosetyl-Al is a fungicide The method modification 00931/M001 presented in this report was validated in order to suppress the steps of derivatization and clean up, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00931 from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
Table 15: LOQ and principle of analytical determination Compound fosetyl-Al Phosphorous acid Determined as fosetyl-Al Phosphorous acid Calculated as fosetyl-Al Phosphorous acid Principle of Determination LC/MS/MS LC/MS/MS
LOQ [mg/L] Drinking water 0.0001 0.0001 Surface water 0.0001 0.0001 1.1. Citation of the Original Method Original Method: 00931 Compounds Fosetyl-Al and its metabolite (phosphorous acid) Author : L. Baudet - R. Diot - M. Guillet - J. L. Kieken Aventis CropScience Centre de Recherche de la Dargoire 14/20 rue Pierre Baizet 69009 Lyon - France Citation : Agredoc Numbers: R011760 and R011761 dated May 22, 2000 Reason for Modification = Suppress the steps of derivatization and clean up.
= Change analysis and detection modes from GC/FPD to LC/MS/MS.
= Decrease the LOQ from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L
for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
1.2. Physical and Chemical Properties See example 3.
2. Experimental Section 2.1. Materials 2.1.1. Apparatus Standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
5 To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
= Balances :
- accuracy 0.1 mg (analytical standards) (e.g. Mettler AT261 range) - accuracy 0.1 g (samples) (e.g. Mettler PM6000) = Dilutor (e.g. Hamilton MicroLab 1000) 10 = Rotary shaker (e.g. Heidolph REAX 2) = Sample Concentrator (e.g. Techne dri-block) = Ultrasonic bath = HPLC (e.g. Binary Pump Agilent 1100) = Auto sampler (e.g. CTC Analytics HTC PAL) 15 = Triple Quadrupole HPLC-MS/MS Mass Spectrometer (e.g. Sciex Instruments, API 4000 System) = Column (e.g. Hypercarb, 100 x 2.0 mm, 5 pm ) 2.1.2. Reagents and Supplies = Acetone (e.g. SupraSolv Merck) = Methanol (e.g. SupraSolv Merck) 20 = Formic acid (e.g. Normapur Prolabo) = Cationic resin (AG 50W-X8, 20-50 Meshs, hydrogen form) (e.g. Bio Rad) = GF/A filters (125mm), (e.g. Whatman) = Polypro bottles (125 mL, wide opening) (e.g. Nalgen) = Polypro bottles (1000 mL, wide opening) (e.g. Nalgen) 25 = Pyrex glass test tubes (20 x 150mm) (e.g. Corning) = Polypro funnels (67mm) (e.g. Marylands Plastics) = Glass disposable pipettes (5 mL) = Solvent for dilution Water with 0.5 % HCOOH
= Mobile phase solvent: Water with 2 % HCOOH
Compound Precursor Ion Product Ion Dwell Time Collision Energy Q1 Mass (amu) Q3 Mass (amu) (msec) (V) fosetyf-AI 109.0 80.9 200 -38 Phosphorous acid 80.9 62.9 600 -16 Table 3: Mass spectrometer scan parameters for the quantifier ions used. The detailed instrument settings used are given in chapters 2.3.1 and 2.3.2. Varying instrument systems or instrument parameters may result in different ion transitions and different relative intensities.
Note: Some mass spectrometer conditions are instrument specific. The spectrometer conditions should be optimised by a competent operator prior to analysis.
Details on MS/MS and LC conditions are given in Appendix 2.
The fragmentation pathways for the quantifier ions for fosetyl-Al and phosphorous acid are shown in Figure 1 and in Figure 2.
Figure 1: Proposed fragmentation pathway for fosetyl-Al.
0 I - loss of C2H4 0 I
H3C-H-p-p-O Hp-P-p ' m/z 109 m/z 81 Figure 2: Proposed fragmentation pathway for phosphorous acid.
0 - loss of H20 -H
m/z 81 m/z 63 2.3.3 Confirmatory transitions 5 To confirm or exclude some interference or pollution in samples, the following transitions can be used in the same conditions described above :
Compound Precursor Ion Product Ion Dwell Time Collision Energy (V) Q1 Mass (amu) Q3 Mass (amu) (msec) fosetyl-Al 109 63 200 -38 phosphorous acid 80.9 78.9 600 -22 The fragmentation pathways for the confirmatory transitions for fosetyl-Al and phosphorous acid 10 are shown in Figure 3 and in Figure 4.
Figure 3: Proposed fragmentation pathway for fosetyl-Al I I - loss of C2H4 -O
H2 H and H20 m/z 109 m/z 63 Figure 4: Proposed fragmentation pathway for phosphorous acid II - loss of H2 -H
15 m/z81 m/z79 Note : all recovery samples were also analysed using confirmatory transitions.
The results are given in Appendix 3.
2.4 Linearity of the Detector The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L.
Table 4: Standard concentrations prepared for the determination of detector linearity. The concentration corresponding to the LOQ is given in the second column of the table.
HPLC-MS/MS Standard Concentrations [Ng/L]
fosetyl-Al 0.1 0.2 0.5 1 2 5 phosphorous acid Table 5: Standard concentrations used for wheat samples and prepared for the determination of detector linearity. The concentration corresponding to the LOQ is given in the second column of the table.
HPLC-MS/MS Standard Concentrations [pg/L]
fosetyl-Al 031 0.5 0.83 1 2.5 5 8.3 phosphorous 3.1 5 8.3 10 25 50 83 acid 2.5 Storage Stability of Extracts The stability of sample extracts containing fosetyl-Al and phosphorous acid was determined for each sample material.
For this purpose, the final extract of recovery samples were stored in the auto sampler rack thermo stated at about 10 C after initial analysis and re-analysed after a storage period of several days.
2.6 Calculation 2.6.1 Calculation of Residues Evaluation in this case is performed according to the external standardisation using matrix matched standards.
During the analysis of each set of samples, the 6 (or 7 for wheat samples) standard solutions mentioned in Table 4 are injected once. Standards should be interspersed with samples to compensate for any minor change in instrument response.
For each compound, the peak area is plotted versus the concentration in order to establish a calibration curve obtained by linear regression weighting 1/x with least squares method.
The corresponding model to determine the concentration in final extracts is calculated using the Analyst Software (Version 1.4).
Each final extract is injected once using the same conditions as previously described for the standard solutions.
Using the predicting mathematical model previously established, the final concentration in Ng/L
of each compound is determined for each injection.
For each compound, the amount of residue R, expressed in mg/kg is calculated, using the following formula :
R= CxVxD
1000x C7 where: R : Determined amount of residue of fosetyl-Al or phosphorous acid in mg/kg C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in pg/L
V : Volume of the extract A in mL, here 200 mL
D : Dilution factor to obtain the Final Extract, here 5 (or 2 for wheat samples) G : Sample weight of analytical sample in g, here 20 g 2.6.2 Calculation of Recovery Rates The concentration of each compound in pg/L is determined for the recovery sample according to 2.6.1.
The percent recovery rate is then calculated as folfows :
CX1oo Rec =
A
where: Rec : Recovered amount found in fortified sample in %
C : Concentration of fosetylAl or phosphorous acid found in the analysed extract in pg/L
A : Fortified amount of fosetyl-Al or phosphorous acid in pg/L
2.6.3 Calculation of Relative Standard Deviation (RSD) The RSD is calculated as follows :
RSD (%) = S.D. / Mean Recovery x 100 %
E (R; - Rm)2 R; : recovery S.D. = [ 1 1iz Rm : mean recovery n-1 n : number of recoveries 3 Results and Discussion 3.1 Specificity and Selectivity The method allows the determination of fosetyl-Al and its metabolite (phosphorous acid) in/on grape, orange, lettuce, cucumber, avocado and wheat samples.
The specificity of the method resulted from the HPLC separation in combination with the very selective MS/MS detection.
3.2 Apparent residues in Control Samples Two control samples were analysed for each sample material. The origin of the control materials used is listed in Table 6.
Table 6: Origin of untreated control samples Sample Material Origin Grape (whole fruit) Mr Lusson - Angers - France Orange (whole fruit) Market specialised in organic food - France Lettuce (head) Market specialised in organic food - France Cucumber (whole fruit) Market specialised in organic food - France Avocado (whole fruit) Control sample from Bayer CropScience - Monheim -Germany Wheat (Grain) Control sample from Bayer CropScience - Monheim - Germany A residue level estimation in control samples was performed. The results are listed in Table 7.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and < 0.03 mg/kg of phosphorous acid.
Table 7: Apparent residues in untreated control samples for fosetyl-Al and phosphorous acid Sample Control Sample LOQ Apparent residues Material [mg/kg] [mg/kg]
fosetyl-AI phospho- fosetyl-Al phospho-rous acid rous acid Grape (whole Mr Lusson - Angers - 0.01 0.1 < 0.003 < 0.03 fruit) FRANCE
Orange Market specialised in organic 0.01 0.1 < 0.003 < 0.03 (whole fruit) food - France Lettuce Market specialised in organic 0.01 0.1 < 0.003 < 0.03 (head) food - France Cucumber Market specialised in organic 0.01 0.1 < 0.003 < 0.03 (whole fruit) food - France Avocado Control sample from Bayer (whole fruit) CropScience - Monheim - 0.01 0.1 < 0.003 < 0.03 Germany Wheat (Grain) Control sample from Bayer CropScience - Monheim - 0.01 0.1 < 0.003 < 0.03 Germany 3.3 Linearity of the Detectors and Matrix Effects The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
5 The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 Ng/L and I and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L.
Experimental details can be found in Chapter 2.4.
In each chromatogram, the measured peak area of fosetyl-Al or phosphorous acid is plotted 10 versus the corresponding concentration of respectively fosetyl-Al or phosphorous acid contained in each standard solution, in order to obtain calibration curve of the form y = ax+b (1/xweighting) where : y = peak area, x = concentration in injected standard solution 15 The results of the determination of detector response for LC/MS/MS are summarised in Table 8.
Table 8: Summary of the determination of detector linearity for LC/MS/MS.
phosphorous Detection Parameter fosetyl-Al acid LC/MS/MS Linear range [pg/Lj 0.1 - 5 1- 50 (or 0.31 - 8.3 for (or 3.1 - 83 for wheat) wheat) ............... .W........................ ................................
.._ ......_._........m.............................................................
No. of concentrations 6 6 (or 7 for wheat) (or 7 for wheat) No. of injections 1 1 Model 1/x weighted 1/x weighted linear regression linear regression Correlation coefficient (R) > 0.9990 > 0.9900 for standards prepared in solvent Correlation coefficient (R) > 0.9990 > 0.9985 for matrix matched standards An excellent linear correlation between the injected amount of the analytes and the detector responses of LC/MS/MS was observed for standards in the range of 0.1 to 5 pg/L
(or 0.31 to 8.3 pg/L for wheat) for fosetyl-Al and in the range of 1 to 50 pg/L (or 3.1 to 83 pg/L for wheat) for phosphorous acid, using either standards prepared in solvent or matrix matched standards.
The occurrence of matrix effects was monitored. The results are shown in Table 9 and table 10.
Table 9: Matrix effect evaluation for fosetyl-Al FL: Fortification Level Measurement using Number Sampfe Material FL of Values Standards in pure Matrix matched [mg/kg] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
Grape (whole fruit) 0.01 5 100 3.1 100 2.9 0.10 5 102 0.9 101 0.9 Orange (whole fruit) 0.01 5 90 6.3 97 6.0 0.10 5 90 4.6 92 4.5 Lettuce (head) 0.01 5 108 6.1 108 6.2 0.10 5 105 1.7 105 2.1 Cucumber (whole fruit) 0.01 5 97 2.1 96 1.6 0.10 5 98 2.3 101 2.7 Avocado (whole fruit) 0.01 5 99 4.9 96 5.0 0.10 5 87 1.9 87 1.9 Wheat (Grain) 0.01 5 87 5.5 88 5.4 0.10 5 74 5.3 73 5.5 Tabie 10: Matrix effect evaluation for phosphorous acid FL: Fortification Level Measurement using Number Sample Material FL of Values Standards in pure Matrix matched [mg/kg] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
0.1 5 156 6.7 99 8.5 Grape (whole fruit) 1 5 131 1.9 102 2.1 Orange (whole fruit) 0.1 5 189 10.6 76 18.3 1 5 147 2.5 98 2.3 Lettuce (head) 0.1 5 193 6.4 81 9.7 1 5 160 3.8 104 3.9 Cucumber (whole fruit) 0.1 5 185 4.7 87 7.0 1 5 135 2.6 100 2.2 Avocado (whole fruit) 0.1 5 139 3.7 73 5.1 1 5 132 6.8 100 6.7 Wheat (Grain) 0.1 5 152 8.3 98 5.8 1 5 163 2.6 79 2.5 In all the sample materials, the measurement of phosphorous acid must be established using matrix matched standards. So the measurement of both compounds is established using matrix matched standards.
3.4 Limit of Quantification and Recovery Experiments The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of <_ 20% could be obtained. The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), fettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
To validate the method for these matrices, samples were fortified with a defined amount of fosetyl-Al and phosphorous acid prior to analysis.
3.5 Recovery Rates The detailed recovery results obtained are listed in Table 11 and Table 12.
Table 11: Recovery rates obtained for fosetyl-Al, FL: fortification level, RSD: relative standard deviation FL Recovery of fosetyl-Al Crop Sample Material [m9/kg] Single Values [%] Mean [%] RSD [%]
Grape Whole fruit 0.01 102 102 95 100 2.9 .......... .................... _............... ......
........................ .... _................. ................
_...................................... ... ..................... ......
............ ....................... _...... .......... _...................
_..........
0.1 101 102 102 101 0.9 Overall Mean and RSD 101 2.1 Orange Whole fruit 0.01 102 100 98 97 6.0 ...................................... _..... ........ .. ..............
....................
....._....__................................................... _............
_.._................ ................. _........................... ........
................ ...... _._.......
0.1 96 95 94 92 4.5 Overall Mean and RSD 95 5.6 Lettuce Head 0.01 104 98 109 108 6.2 ...... ................. ........ ............... ..... _.................
__......... _..._......... .................................................
...._.._......... .._............................. ........... .....
_......................... _..........
0.1 102 106 104 105 2.1 Overall Mean and RSD 106 4.5 Cucumber Whole fruit 0.01 95 96 98 96 1.6 0.1 106 101 101 101 2.7 Overall Mean and RSD 99 3.4 Avocado Whole fruit 0.01 104 95 92 96 5.0 ................ ............... ........
.........................................................
_........................................................
.............................................. ..............
_........................ _....
0.1 88 88 85 87 1.9 Overall Mean and RSD 91 6.1 Wheat Grain 0.01 86 92 93 88 5.4 _..... . ........................................
................................................................ .........
._..................... _........................... _.......... .......
_............ ......................... ..._. . .
...................................
0.1 75 79 69 73 5.5 Overall Mean and RSD 80 10.9 Table 12: Recovery rates obtained for Phosphorous acid, FL: fortification level, RSD: relative standard deviation FL Recovery of Phosphorous acid Crop Sample Material [mg/kg] Single Values [%] Mean [%] RSD [%]
Grape Whole fruit 0.1 96 94 113 99 8.5 ...................................................... ....................
........................................................................._.....
..............,.......__....... ............ _...... ........ _..............
..............................................
1 100 105 104 102 2.1 Overall Mean and RSD 101 6.0 Orange Whole fruit 0.1 65 99 70 76 18.3 1 97 99 101 98 2.3 Overall Mean and RSD 87 17.3 Lettuce Head 0.1 82 94 76 81 9.7 ..... _ ............................................. ....... __.......
.__........................................ _.._.........
_.................................... .... ..........
.......................... ............. _.....
................................... _.........
1 103 108 98 104 3.9 Overall Mean and RSD 93 14.7 Cucumber Whole fruit 0.1 83 82 82 87 7.0 1 102 102 101 100 2.2 Overall Mean and RSD 93 8.9 Avocado Whole fruit 0.1 74 77 68 73 5.1 1 110 97 92 100 6.7 Overall Mean and RSD 87 17.8 Wheat Grain 0.1 90 94 101 98 5.8 .. ............................ _.._.. ....... . ..............
........................... _...................... _.__........
........................................................
....................... ............ _.........
.................................... __......
1 77 77 81 79 2.5 Overall Mean and RSD 89 12.2 The obtained recovery rates are summarised below in Table 13.
In total 60 recovery rates were determined for each compound. The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60).
Table 13: Summary of the recovery data for the determination of accuracy and repeatability;
RSD: relative standard deviation Parameter Phospho-rous rous acid Accuracy Single recoveries [%] 69 - 114 65 - 113 Mean recoveries per fortification level [%] 93 - 97 86 - 97 Mean recoveries per sample material [%] 80 - 106 87 - 101 Overall mean [%] 95 91 Number of values n 60 60 Repeatability RSD per fortification level [%] 7.6 - 12.3 9.5 -14.9 RSD per sample material [%] 2.1 - 10.9 6.0-17.8 Overall RSD [%] 10.2 13.7 3.6 Storage Stability of Extracts The stability of final extracts containing fosetyl-Al and its metabolite phosphorous acid was determined. For this purpose, the final extracts of recovery samples were let in the auto sampler rack thermo stated at about 10 C after initial analysis and re-analysed after a storage period of several days.
The results of the storage stabilities are detailed in Table 14.
Table 14: Stability period of final extracts in the auto sampler rack at about Sample Material Stability period (days) Grape (whole fruit) 7 days Orange (whole fruit) 4 days Lettuce (head) 8 days Cucumber (whole fruit) 8 days Avocado (whole fruit) 4 days Wheat (Grain) 3 days 4 Evaluation and Discussion The presented residue analytical method modification 00861/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit),avocado (whole fruit), and wheat (grain) by LC/MS/MS.
fosetyl-Al and its metabolite (phosphorous acid) were extracted from the sample material with a mixture of acetonitrile/water (50/50). After centrifugation and dilution of the sample material, the residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation in matrix matched standards The validation set included the determination of the detector linearity, the limit of quantification, the accuracy of the method and the storage stability of sample final extracts.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L. The detector response was linear in these ranges.
The occurrence of matrix effects was monitored.
In all the sample materials, the measurement of phosphorous acid must be established using matrix matched standards. So the measurement of both compounds is established using matrix matched standards.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and < 0.03 mg/kg of phosphorous acid.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of <_ 20% could be obtained. The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so that this method modification has been validated successfully.
Appendix 1 Flow Diagram of Residue Method 00861/M001 Extraction 1. Weigh 20.0 g of homogeneous sample material into a 125 mL polypropylene bottle.
2. Add 80 mL of acetonitrile / water (50/50, v/v).
3. Blend the sample using a high-speed blender (IKA or equivalent) for approx. 5 minutes.
4. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
5. Pour the supernatant into a 200 mL volumetric flask.
6. Add 80 mL of acetonitrile / water (50/50, v/v) on the bottom.
7. Blend the sample using a high-speed blender (IKA or equivalent) for approx. 5 minutes.
8. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
9. Pour the supernatant into the volumetric flask.
10. Make-up to 200 mL with methanol. This is the Extract A.
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. Filter the extract through an Acrodisc CR 25 mm PTFE filter (0.45 pm).
13. Dilute five times the extract using acidified methanol with formic acid 0.5 %. This is the Final Extract.
Remark : for wheat samples, from stage 10, follow the preparation as described below :
10. Add 1 mL of concentrated formic acid and make-up to 200 mL with methanol. This is the Extract A.
11. Centrifuge an aliquot of about 10 mL of Extract A (6000 rpm - ambient) for approx. 10 minutes.
12. With dilutor, dilute twice the supernatant using acidified methanol with formic acid 0.5 %.
13. Filter the extract through an Acrodisc CR 25 mm PTFE filter (0.45 pm). This is the Final Extract.
HPLC Measurement with Electrospray MS/MS detection Appendix 2 Details on LC-MS/MS conditions Comment:
Synchronization Mode: LC Sync Auto-Equilibration: Off Acquisition Duration: 11 min59sec Number Of Scans: 888 Periods In File: 1 Acquisition Module: Acquisition Method Software version Analyst 1.4 MS Method Properties:
Period 1:
--------------Scans in Period: 888 Relative Start Time: 0.00 msec Experiments in Period: 1 Period 1 Experiment 1:
----------------------------Scan Type: MRM (MRM) Polarity: Negative Scan Mode: N/A
Ion Source: Turbo Spray Resolution Q1: Unit Resolution Q3: Unit Intensity Thres.:0.00 cps Settling Time: 0.0000 msec MR Pause: 5.0070 msec MCA: No Step Size: 0.00 amu Quantifier transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 62.90 600.00 DP -55.00 -55.00 (phosphorous acid) CE -38.00 -38.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 109.00 80.90 200.00 DP -45.00 -45.00 (fosetyl-AI) CE -16.00 -16.00 Parameter Table (Period 1 Experiment 1):
CUR: 20.00 GS1: 40.00 GS2: 60.00 IS: -4500.00 TEM: 600.00 ihe: ON
CAD: 6.00 EP -10.00 CXP -1.00 Confirmatory transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 78.90 600.00 DP -55.00 -55.00 (phosphorous acid) CE -22.00 -22.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 109.00 63.00 200.00 DP -45.00 -45.00 (fosetyl-Al) CE -38.00 -38.00 Parameter Table (Period 1 Experiment 1):
CUR: 20.00 GS1: 40.00 GS2: 60.00 IS: -4500.00 TEM: 600.00 ihe: ON
CAD: 6.00 EP -10.00 CXP -5.00 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Binary Pump Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Dead Volume (pl): 40.0 Maximum Flow Ramp (ml/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 Step Table:
Step Total Time(min) Flow Rate(pl/min) A(%) B(%) 0 0.00 400 65.0 35.0 1 10.00 400 65.0 35.0 Left Compressibility: 50.0 Right Compressibility: 115.0 Left Dead Volume (pl): 40.0 Right Dead Volume (pl):40.0 Left Stroke Volume (pl): -1.0 Right Stroke Volume (NI): -1.0 Left Solvent: A2 (water + 0.5% formic acid) Right Solvent: B2 (methanol) CTC PAL Auto sampler Method Properties :
Loop Volumel (pl): 100 Loop Volume2 (pI): 20 Injection Volume (pI): 50.000 Method Description:
Syringe: 250u1 Analyst LC-Inj Air Volume (pI) 0 Pre Clean with Solvent 1O 2 Pre Clean with Solvent 2() 1 Pre Clean with Sample () 0 Filling Speed (NI/s) 50 Filling Strokes () 0 Inject to LC VIv2 Injection Speed (pUs) 50 Pre Inject Delay (ms) 500 Post Inject Delay (ms) 500 Post Clean with Solvent 1() 3 Post Clean with Solvent 2() 2 Valve Clean with Solvent 1() 2 Valve Clean with Solvent 2() 1 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Quaternary Pump Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Compressibility: 100.0 Dead Volume (pI): 40.0 Stroke Volume (NI): -1.0 Maximum Flow Ramp (ml/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 Step Table:
Step Total Time Flow Rate A(%) B(%) C( /o) D(%) TE#1 TE#2 TE#3 TE#4 (min) (taUmin) (water) (methanol) 0 0.00 200 50.0 50.0 0.0 0.0 open open open open 1 10.00 200 50.0 50.0 0.0 0.0 open open open open Primary Flow Rate (ul/min): 200.0 Flow Sensor Calibration Table Index: 0 Valco Valve Method Properties Valco Valve Diverter Total Time (min) Position 1 0.0 B waste 2 3.0 A spectro Gas pressure Auto sampler CTC Analytics HTS Pal n 1303 N2 4 bar Peltier rack 10 C
Air gas 7.5 bar Loop 20 pL
Air Exhaust gas 4 bar Solvent 1 H20 + 0.5 % HCOOH
Solvent 2 MeOH
Oven Agilent G1316A n 1294 Tem erature Not used Valco valve Column selector n 1289 n 1290) Ten ports 6 positions 2 positions Not used A = MS B = Waste Pumps Source Probe TurbolonSpray n 1291 Binary pump Agilent 1100 G1312A 133 bar n 1288 n 1297) Flow 0.4 mL/min Horizontal Position 7 (x axis) A2 = H20+ 0.5% Formic Acid 65 % Vertical Position 7 axis) B2=MeOH 35%
Ca illa exit 1 mm Isocratic Mass Spectrometer API 4000 Device GLP n 1292 Quaternary pump Agilent 1100 G1354A n 1298 Flow 0.2mL/min Column A = H20 50 % Precolumn SMPREA1 B = MeOH 50 % Column SMAR 69-1 C = - Thermo Hypercarb 100 x 3.0mm 5 m D = - (ambient tem erature lsocratic mode Appendix 3 Results obtained with confirmatory transitions FL Recovery of fosetyl-Al Crop Sample Material [mg/kg] Single Values [%] Mean [%] RSD [%]
Grape Whole fruit 0.01 101 107 106 100 8.8 0.1 98 102 93 99 4.5 Overall Mean and RSD 99 6.7 Orange Whole fruit 0.01 121 121 110 110 10.3 ..... ..... ................ _............. _.......
........................................................ ...........
_......... ........ . ...........................................
_............ .__._.._.._.................. ............... ..... _.....
_..... ........ _ 0.1 98 102 91 94 7.0 Overall Mean and RSD 102 12.2 Lettuce Head 0.01 113 102 90 97 10.9 .................. _... _............ .. _..... .....
_........................... _........ _..... .
..................................................... _ _..............
.................................... _....... .......................
_............. _.....
0.1 95 97 96 96 1.4 Overall Mean and RSD 97 7.4 Cucumber Whole fruit 0.01 117 117 107 110 6.0 0.1 100 100 102 100 1.4 Overall Mean and RSD 105 6.6 Avocado Whole fruit 0.01 93 94 91 92 4.9 0.1 85 87 85 85 1.4 Overall Mean and RSD 89 5.4 Wheat Grain 0.01 83 88 98 89 7.3 ............. -_................................... .........................
................ _..._-.............. ..................................... .
_................... ......... ........... ......... _.... __....... .........
.. .... _........................... _........
0.1 72 81 73 75 5.2 Overall Mean and RSD 81 10.8 Grape Whole fruit 0.1 91 86 119 96 14.1 ............................................. ................... .........
..._._............ . .......................................................
_............... _.............. _.......................... _.... ..........
.................... ...........................
1 99 101 98 100 1.6 Overall Mean and RSD 98 9.6 Orange Whole fruit 0.1 69 92 68 74 14.1 .................................. _................ ........
_................... ..... . ........................... _........
_........... ........................................ _........... ........
_.....................................
..............................................
1 108 106 106 104 4.3 Overall Mean and RSD 89 19.8 Lettuce Head 0.1 91 80 94 81 14.3 ......... .................. ..._.....
...............................................................................
....... ..................... ....................... _.....
....................... _.. .... ....... ..._.... _........... .__.......
_......
1 103 105 101 102 2.0 Overall Mean and RSD 91 14.9 Cucumber Whole fruit 0.1 90 93 77 86 9.9 ................................. . ........... ............................
_.... .............. . ........... .
................................................. _ _.....................
................ ......................... ............... _.. _...........
_...........
1 101 100 101 99 2.5 Overall Mean and RSD 93 9.8 Avocado Whole fruit 0.1 71 81 84 76 8.0 1 113 107 103 104 5.5 Overall Mean and RSD 90 17.5 Wheat Grain 0.1 74 74 77 74 2.9 ......................................... _........... ..__.....
........................... _. ........ ........... __...................
_.............. ........... . .................. ........
_.................... ................ .........._............................
....
1 75 82 78 80 4.0 Overall Mean and RSD 77 5.1 FL : Fortification Level Example 4:
This detailed example concerns the analysis of fosetyl-Al and of phosphorous acid using water samples. This example is a modification M001 to the Analytical Method 00931 for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in/on drinking water and surface water by LCMSMS.
The presented residue analytical method modification 00931/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in drinking water and surface water by LC/MS/MS.
The sample material is treated with a cationic resin and then concentrated.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation.
The quantification was done by an external standardisation in matrix matched standards.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.2 and 20 pg/L.
The occurrence of matrix effects was monitored. In drinking water, the measurement of fosetyl-Al must be established using matrix matched standards. The results obtained with standards in pure solvent for phosphorous acid in both sample materials do not always comply with European requirements. So the measurement of both compounds in drinking water and surface water is established using matrix matched standards.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.00003 mg/L.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of 20% could be obtained.
The LOQ was set at 0.0001 mg/L for each compounds in drinking water and surface water.
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 75 to 118 % for fosetyl-Al and of 72 to 117 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 89 to 96 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 93% and of 91 to 93 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 92 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
The relative standard deviations (RSD) for the single fortification levels ranged from 9.6 to 14.3 % for fosetyl-Al and from 8.8 to 19.8 % for phosphorous acid (n=10).
The overall RSD values per sample material were between 7.5 and 9.7 % for fosetyl-Al and 9.3 and 12.4 % for phosphorous acid (n=10). The RSD value across all samples was 12.7 % for fosetyl-Al and 15.0 % for phosphorous acid (n=20). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so this method modification has been validated successfully.
A variant method was also validated on drinking water and surface water. The sample preparation of the main method was strongly simplified by the suppression of the concentration step. The variant method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996), for non concentrated drinking water and surface water at 0.1 Ng/L
for fosetyl-Al and ten times this limit for fosetyl-Al and at 1 pg/L for phosphorous acid when matrix matched standards were used, independently of the LC conditions tested.
Regarding to the main method, the sample preparation was greatly simplified and allows to save a lot of time.
1. Introduction Fosetyl-Al is a fungicide The method modification 00931/M001 presented in this report was validated in order to suppress the steps of derivatization and clean up, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00931 from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
Table 15: LOQ and principle of analytical determination Compound fosetyl-Al Phosphorous acid Determined as fosetyl-Al Phosphorous acid Calculated as fosetyl-Al Phosphorous acid Principle of Determination LC/MS/MS LC/MS/MS
LOQ [mg/L] Drinking water 0.0001 0.0001 Surface water 0.0001 0.0001 1.1. Citation of the Original Method Original Method: 00931 Compounds Fosetyl-Al and its metabolite (phosphorous acid) Author : L. Baudet - R. Diot - M. Guillet - J. L. Kieken Aventis CropScience Centre de Recherche de la Dargoire 14/20 rue Pierre Baizet 69009 Lyon - France Citation : Agredoc Numbers: R011760 and R011761 dated May 22, 2000 Reason for Modification = Suppress the steps of derivatization and clean up.
= Change analysis and detection modes from GC/FPD to LC/MS/MS.
= Decrease the LOQ from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L
for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
1.2. Physical and Chemical Properties See example 3.
2. Experimental Section 2.1. Materials 2.1.1. Apparatus Standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
5 To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
= Balances :
- accuracy 0.1 mg (analytical standards) (e.g. Mettler AT261 range) - accuracy 0.1 g (samples) (e.g. Mettler PM6000) = Dilutor (e.g. Hamilton MicroLab 1000) 10 = Rotary shaker (e.g. Heidolph REAX 2) = Sample Concentrator (e.g. Techne dri-block) = Ultrasonic bath = HPLC (e.g. Binary Pump Agilent 1100) = Auto sampler (e.g. CTC Analytics HTC PAL) 15 = Triple Quadrupole HPLC-MS/MS Mass Spectrometer (e.g. Sciex Instruments, API 4000 System) = Column (e.g. Hypercarb, 100 x 2.0 mm, 5 pm ) 2.1.2. Reagents and Supplies = Acetone (e.g. SupraSolv Merck) = Methanol (e.g. SupraSolv Merck) 20 = Formic acid (e.g. Normapur Prolabo) = Cationic resin (AG 50W-X8, 20-50 Meshs, hydrogen form) (e.g. Bio Rad) = GF/A filters (125mm), (e.g. Whatman) = Polypro bottles (125 mL, wide opening) (e.g. Nalgen) = Polypro bottles (1000 mL, wide opening) (e.g. Nalgen) 25 = Pyrex glass test tubes (20 x 150mm) (e.g. Corning) = Polypro funnels (67mm) (e.g. Marylands Plastics) = Glass disposable pipettes (5 mL) = Solvent for dilution Water with 0.5 % HCOOH
= Mobile phase solvent: Water with 2 % HCOOH
30 Methanol with 2 /a HCOOH
2.1.3. Reference Item See example 3.
2.1.4. Standard Solutions Stock and standard solutions were stored protected from light in a refrigerator at around 5 C.
35 Stock solutions 0 000 mg/L) Into a 100 mL amber screw-cap flask, weigh accurately between 20 and 50 mg of reference item. Using a burette, add a volume of water to obtain a stock solution of exactly 1000 mg/L. Mix thoroughly until complete dissolution using a magnetic stirrer. Two separate stock solutions must be prepared for each compound. After comparison of these two stock solutions, they are mixed.
Mixture solution Pipette 5 mL of each stock solution using a class "A+" pipette. Pour into a class "A" 50 mL
volumetric flask. Adjust volume with water, cap and mix by shaking (100 mg/L
of each compound).
Fortifying standard solutions By serial dilutions of the mixture solution in water, prepare the fortifying standard solution used for recoveries at 10LOQ level (0.1 mg/L of each compound) and the fortifying standard solution used for recoveries at LOQ level (0.01 mg/L of each compound).
Intermediate standard solution By serial dilutions of the mixture solution, prepare the intermediate standard solution at 1.0 mg/L
using water.
Standard solutions in solvent To obtain the standard solutions used for calibration, dilute extemporaneously using a dilutor and water with 0.5% formic acid, the intermediate standard solution to obtain the following concentrations: 0.2, 0.4, 0.5, 0.75, 1, 2, 5, 10 and 20 pg/L.
Matrix matched standard solutions used for calibration The occurrence of matrix effects was monitored and the measurement of both compounds is established using matrix matched standards in both sample materials.
From the intermediate standard solution, the dilutions are the same as preparation of standard solutions in solvent, except the dilution mixture which is the final extract of a control sample.
Remarks :
= 20 to 25 mL of final extract are necessary to make all dilutions.
= final extracts of control sample could be prepared a day before use and stocked in a refrigerator.
2.1.5. Stability of the standard solutions The stock solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 9 months and a half.
2.2. Residue Analytical Methodology Some modifications compared to the original analytical method were introduced.
The method modification 00931/M001 presented in this report was validated in order to suppress the steps of derivatization and clean up, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00931 from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
= The Limit of Quantification was decreased from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
= The NaOH treatment was replaced by a resin treatment.
= The derivatization step was supressed.
= The clean-up step with liquid-liquid partition was suppressed.
= The quantification was carried out by LC/MS/MS instead of GC/FPD.
All modifications were included in the description below.
A flow chart of the method is given in Appendix 1.
Note : during analysis, for each sample set, it is necessary to do a blank reagent where water sample is replaced by Milli Q water to be sure that no phosphorous acid contamination (< 30%
LOQ) coming from sample preparation is found.
Remark : standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
For recovery experiments, samples are fortified by adding the appropriate standard solution to the sample material after weighing and before shaking.
Preparation of the cationic resin :
15. Weigh about 25 g of AG 50W-X8 resin into a 1000 mL polypropylene bottle.
16. Add about 500 mL of water.
17. Shake using a rotary shaker for about 10 minutes.
18. Discard the supernatant water.
19. Do steps 2 to 4 a second time.
20. Do steps 2 to 4 a third time.
21. Filtrate residual water and resin through two GF/A filters put in a polypropylene funnel and previously rinsed with water.
Remark: resin is prepared either just before use or in advance, stored at ambient temperature and re-hydrated just before use.
Caution: phosphorous acid interferences could be observed if the resin is not washed as described above.
Samples preparation :
1. Weigh 0.6 g of AG 50W-X8 resin previously washed into a 125 mL
polypropylene bottle.
2. Using disposable Pasteur pipette, weigh 20.0 g of homogeneous sample material into the bottle.
Note: weight of the sample is used for residue calculation, addressed as variable Wwater 3. Shake the sample using a rotary shaker for 10 minutes. This is the Extract A.
Note: The weight of Extract A is used for residue calculation, addressed as variable WExtraCc In this case, there was no extraction: no solvent was added to water sample;
it was just a resin treatment, so WExtract = Wwater = 20 g 4. Using a disposable glass pipette, transfer an aliquot of 5 mL of supernatant into a test tube previously weighted.
Note: The volume of aliquot is used for residue calculation, addressed as variable VAUqUOt ( Instead of transferring 5 mL, this aliquot could also be done by weighing 5 g= WAi;qõot 5. Evaporate under a nitrogen flow using a sample concentrator at a temperature of about 60 C to approximately 0.5 g. Caution not to evaporate to dryness.
6. Using disposable pipette, make-up to 1.0 g with acidified water with formic acid 0.5 %.
Note: the concentration of formic acid in acidified water used in step 6 is a critical parameter: it has an important action on the H3P03 peak shape obtained in LC.
The increase from 0.5% to 2% of formic acid in acidified water can give a very large H3P03 peak, and accordingly a loss of sensitivity.
7. Sonicate for about 5 minutes. This is the Final Extract.
Note: weight of Final Extract is used for residue calculation, addressed as variable WEnd 8. Proceed to LC/MS/MS measurement, Chapter 2.3.
Note: if it is necessary to dilute the Final Extract due to a concentration outside the calibration curve: use final extract of control sample because matrix matched standards are used for calibration.
2.3. Analysis and Instrument Conditions The final extracts are injected into a high performance liquid chromatograph and detected by tandem mass spectrometry with electrospray ionisation.
The quantification is carried out by external standardisation using matrix matched standards.
Exemplary LC/MS/MS conditions that were used in the course of this method validation are listed in chapters 2.3.1 and 2.3.2. These conditions are given as a guidance and may have to be adapted for other HPLC-MS/MS systems 2.3.1. HPLC Conditions Instrument: Binary pump Agilent 1100 Auto sampler: CTC Analytics HTS PAL
Column: Hypercarb, 100 x 2.0 mm, 5 pm Precolumn: none Injection Volume: 50 pL
Column temperature: ambient (about 25 C) Mobile Phase:
Isocratic mode: 55 / 45 (v/v) Methanol + 2% formic acid / water + 2% formic acid Flow (Column): 200 pL/min Retention Times: from 3.1 to 4.1 min for phosphorous acid and from 3.9 to 5.3 min for fosetyl-Al.
Remarks :
= Retention times in concentrated samples are lightly shorter than in solvent (about 0.2 min in surface water and 0.5 min in drinking water).
= It is necessary to wait about 2 hours the stabilisation of the HPLC system before injecting.
During a samples set, a light drift of retention time of both compounds can be observed.
= Hypercarb precolumn must not be used.
= Depending of the phase batch of Hypercarb column, the percentage of formic acid in the mobile phase could be adapted to improve peaks shape (from 0.5% to 2%).
2.3.2. MS/MS Conditions See example 3.
2.3.3. Confirmatory transitions See example 3.
Note : all recovery samples were also analysed using confirmatory transitions.
The results are given in Appendix 6.
2.4. Linearity of the Detector The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.2 and 20 pg/L.
Table 16: Standard concentrations prepared for the determination of detector linearity. The concentration corresponding to the LOQ is printed in the third column of the table.
HPLC-MS/MS Standard Concentrations [pg/L]
fosetyl-Al 0.2 0.4 0.5 0.75 1 2 5 10 20 phosphorous acid 0.2 0.4 0.5 0.75 1 2 5 10 20 2.5. Storage Stability of Extracts 5 The stability of sample extracts containing fosetyl-Al and phosphorous acid was not determined in this study.
2.6. Calculation 2.6.1. Calculation of Residues Evaluation in this case is performed according to the external standardisation using matrix matched standards.
During the analysis of each set of samples, the 9 standard solutions mentioned in Table 16 are injected once. Standards should be interspersed with samples to compensate for any minor change in instrument response.
For each compound, the peak area is plotted versus the concentration in order to establish a calibration curve obtained by linear regression weighting 1/x with least squares method.
The corresponding model to determine the concentration in final extracts is calculated using the Analyst Software (Version 1.4).
Each final extract is injected once using the same conditions as previously described for the standard solutions.
Using the predicting mathematical model previously established, the final concentration in pg/L
of each compound is determined for each injection.
For each compound, the amount of residue R, expressed in mg/L is calculated, using the following formula :
R C X VEnd X VExtract =
1000 x VWater x VAl;aõot where: R : Determined amount of residue of fosetyl-Al or phosphorous acid in mg/L
C : Concentration of fosetyl-Al or phosphorous acid found in the final extract in Ng/L
VEnd : Volume of the final extract in mL, considering that : VE,d = WE,d x Density -1 where WEnd = weight of the final extract in g, here I g and Density -1 = 1 mL/g (*) VExtract : Volume of the extract A in mL, considering that : VE~tract =
WExtract x Density -1 where WExtract = weight of the extract A in g, here 20 g and Density ~= 1 mL/g (*).
In this case, there was no extraction: no solvent was added to water sample;
it was just a resin treatment, so WExtraot =Wwater = 20 g Vwater : Volume of the anal tical sam le in mL, considering that : Vwater =
Wwater x Density Y p where Wwater = weight of the water in g, here 20 g and Density ~= 1 mL/g (*) VAi;qõot : Aliquot (of extract A) used before evaporation in mL, here1 5 mL
If the aliquot has been weighed, VAliquot = WAUquot x Density where WAi;quot = weight of the aliquot in g, here 5 g and Density ~= 1 mL/g (*) Remarks (*) :
= The density of all liquid samples (water, extracts) is considered equal to 1 independently to room temperature. This allows to convert weight of liquid samples into volume.
= In order to express phosphorous acid in fosetyl-Al equivalent, the ratio of the molecular weight must be used :
354.1 g/mol ~ 0 Ratio = =1.44 (82.0 x 3) g/mol because 1 mole fosetyl-Al (354.1 g) gives 3 moles of phosphorous acid.
2.6.2. Calculation of Recovery Rates The concentration of each compound in pg/L is determined for the recovery sample according to 2.6.1.
The percent recovery rate is then calculated as follows :
Cx100 Rec =
A
where: Rec : Recovered amount found in fortified sample in %
C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in pg/L
A : Fortified amount of fosetyl-Al or phosphorous acid in Ng/L
2.6.3. Calculation of Relative Standard Deviation (RSD) The RSD is calculated as follows :
RSD (%) = S.D. / Mean Recovery x 100 %
E (R; - Rm)2 Ri : recovery S.D. _ [ VVZ
Rm : mean recovery n- 1 n: number of recoveries 3. Results and Discussion 3.1. Specificity and Selectivity The method allows the determination of fosetyl-Al and its metabolite (phosphorous acid) in drinking water and surface water samples.
The specificity of the method resulted from the HPLC separation in combination with the very selective MS/MS detection.
3.2. Apparent residues in Control Samples Two control samples were analysed for each sample material. The origin of the control materials used is listed in Table 17.
Table 17: Origin of untreated control samples Test system Origin Drinking water BCS - CRLD - Tap water from lab D221 - Lyon - France Surface water St Agnan en Vercors - France Some characteristics of surface water are recorded in Table 18.
Table 18: Characteristics of surface water date of pH Ca++ clay particles total organic conductivity collect at 16.5 C (mg/L) (mg/L) carbon (TOC) (pS/cm) (yyyy/mm/dd) (mg/L) (NF T 90-008) (potentiometric (NF EN 872) (NF EN 1484) (NF EN 27 888) detection) 2005/03/27 8.1 88 < 2 1.00 400 These characteristics were determined by :
Cemagref Division qualite des eaux et prevention des pollutions Groupement de Lyon 3 bis quai Chauveau 69336 Lyon cedex 09 - France A residue level estimation in control samples was performed. The results are listed in Table 19.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.00003 mg/L.
Table 19: Apparent residues in untreated control samples for fosetyl-Al and phosphorous acid Sample Origin LOQ Apparent residues Material [mg/L] [mg/L]
fosetyl-AI phospho- fosetyl-Al phospho-rous acid rous acid Drinking BCS - CRLD - Tap water water from lab D221 - Lyon - 0.0001 0.0001 < 30% LOQ < 30 / LOQ
France Surface St Agnan en Vercors -0.0001 0.0001 water < 30% LOQ < 30% LOQ
France 3.3. Limit of detection Control sample fortified at 0.00005 mg/L were analysed to test the limit of detection of fosetyl-Al and phosphorous acid. The results are given in Table 20.
Table 20: Recovery rate obtained for fosetyl-Al and phosphorous acid at 0.05 pg/L fortification level Sample Material Fortification level Recovery [mg/L] [%]
fosetyl-Al phosphorous fosetyl-Al phosphorous acid acid Drinking water 0.00005 0.00005 89 75 Surface water 0.00005 0.00005 106 95 3.4. Linearity of the Detectors and Matrix Effects The linearity of the detector used was tested for fosetyl-A( and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.2 and 20 pg/L.
Experimental details can be found in Chapter 2.4.
In each chromatogram, the measured peak area of fosetyl-Al or phosphorous acid is plotted versus the corresponding concentration of respectively fosetyl-Al or phosphorous acid contained in each standard solution, in order to obtain calibration curve of the form :
y = ax + b (1 /x weighting) where : y = peak area, x = concentration in injected standard solution The results of the determination of detector response for LC/MS/MS are summarised in Table 21.
Table 21: Summary of the determination of detector linearity for LC/MS/MS.
phosphorous Detection Parameter fosetyl-Al acid LC/MS/MS Linear range [Ng/L] 0.2 - 20 0.2 - 20 No. of concentrations 9 9 ............. I............. _................. ...._......
_........................................ _- ....................
_.,.......... _................. _............. ..............................
---.................................. u........ ........ ..
....................... __..............................................
No. of injections 1 1 ....................... _........... . .......................................
_.............. _.... _......................
_.................................. _..... _........ _..... ......
_........... _................. _....... _...---......... _. ...
........................................... ..............................
_.......
Model 1/x weighted 1/x weighted linear regression linear regression ................................................ _...---..................
................... .........................................................
. ........................ ........... ................................ ....
............... ._._................. .....
................................... _.................... ....................
Correlation coefficient (R) > 0.9993 > 0.9991 for standards prepared in solvent Correlation coefficient (R) > 0.9981 > 0.9990 for matrix matched standards An excellent linear correlation between the injected amount of the analytes and the detector responses of LC/MS/MS was observed for standards in the range of 0.2 to 20 pg/L for both compounds, using either standards prepared in solvent or matrix matched standards.
5 The occurrence of matrix effects was monitored. The results are shown in Table 22 and table 23.
Table 22: Matrix effect evaluation for fosetyl-Al.
FL : Fortification Level Measurement using Number Sample Material FL of Values Standards in pure Matrix matched [mg/L] solvent standards (n) Mean [%] RSD [%] Mean [%] RSD [%]
Drinking water 0.0001 5 25 17.0 86 12.2 0.001 5 33 7.0 82 6.5 Surface water 0.0004 5 97 7.9 107 6.4 0.001 5 103 3.4 96 3.3 Table 23: Matrix effect evaluation for phosphorous acid 10 FL : Fortification Level Measurement using Number Sample Material FL of Values Standards in pure Matrix matched [mg/L] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
Drinking water 0.0001 5 80 3.3 76 5.7 0.001 5 64 11.3 88 11.9 Surface water 0.0001 5 123 4.2 109 4.1 0.001 5 101 4.6 93 4.6 In drinking water, the measurement of fosetyl-Al must be established using matrix matched standards. The results obtained with standards in pure solvent for phosphorous acid in both sample materials do not always comply with European requirements. So the measurement of both compounds in drinking water and surface water is established using matrix matched standards.
3.5. Limit of Quantification and Recovery Experiments The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of s 20% could be obtained.
The LOQ was set at 0.0001 mg/L for each compounds in drinking water and surface water.
To validate the method for these matrices, samples were fortified with a defined amount of fosetyl-Al and phosphorous acid prior to analysis.
3.6. Recovery Rates The detailed recovery results obtained are listed in Table 24 and table 25.
Table 24: Recovery rates obtained for fosetyl-Al, RSD: relative standard deviation Fortification Level Recovery of fosetyl-Al Sample Material [mg/L] Single Values [%] Mean [%] RSD [%]
Drinking water 0.0001 76 76 87 86 12.2 ................................ ._.._................... _.......... _.....
_.. ._........................................................... ..........
...........................................................
..............................................
...............................................
0.001 78 75 87 82 6.5 Overall Mean and RSD 84 9.7 Surface water 0.0001 100 103 107 107 6.4 ......... ._.......... ... ...................................... ._ .............. .......... ............. _.................................
_................. ....................................... ................
.............................................
...............................................
0.001 98 100 96 96 3.3 F Overall Mean and RSD 101 7.5 Table 25: Recovery rates obtained for Phosphorous acid, RSD: relative standard deviation Fortification Level Recovery of Phosphorous acid Sample Material [mg/L] Single Values [%] Mean [%] RSD [%]
Drinking water 0.0001 72 72 74 76 5.7 0.001 80 76 89 88 11.9 Overall Mean and RSD 82 12.4 Surface water 0.0001 109 106 106 109 4.1 0.001 97 98 94 93 4.6 Overall Mean and RSD 101 9.3 The obtained recovery rates are summarised below in Table 26.
In total 20 recovery rates were determined for each compound.
The single recovery rates were in the range of 75 to 118 % for fosetyl-Al and of 72 to 117 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 89 to 96 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 93% and of 91 to 93 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 92 %.
The relative standard deviations (RSD) for the single fortification levels ranged from 9.6 to 14.3 % for fosetyl-Al and from 8.8 to 19.8 % for phosphorous acid (n=10).
The overall RSD values per sample material were between 7.5 and 9.7 % for fosetyl-Al and 9.3 and 12.4 % for phosphorous acid (n=10). The RSD value across all samples was 12.7 % for fosetyl-Al and 15.0 % for phosphorous acid (n=20).
Table 26: Summary of the recovery data for the determination of accuracy and repeatability;
RSD: relative standard deviation Parameter Phospho-fosetyl-AI
rous acid Accuracy Single recoveries [%] 75 - 118 72 - 117 Mean recoveries per fortification level [ lo] 89 - 96 91 - 93 Mean recoveries per sample material [%] 84 - 101 82 - 101 Overall mean [%] 93 92 Number of values n 20 20 Repeatability RSD per fortification level [%] 9.6 - 14.3 8.8 - 19.8 RSD per sample material [%] 7.5 - 9.7 9.3 - 12.4 Overall RSD [%] 12.7 15.0 3.7. Storage Stability of Extracts The stability of sample extracts containing fosetyl-Al and phosphorous acid was not determined in this study.
4. Evaluation and Discussion The presented residue analytical method modification 00931/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in drinking water and surface water by LC/MS/MS.
The sample material is treated with a cationic resin and then concentrated.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation.
The quantification was done by an external standardisation in matrix matched standards.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L. The detector response was linear in these ranges.
The occurrence of matrix effects was monitored.
In all the sample materials, the measurement of phosphorous acid must be established using matrix matched standards. So the measurement of both compounds is established using matrix matched standards.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and < 0.03 mg/kg of phosphorous acid.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of <_ 20% could be obtained. The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
the relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue 5 analytical methods, so this method modification has been validated successfully.
Note : during analysis, for each sample set, it is necessary to do a blank reagent where water sample is replaced by Milli Q water to be sure that no phosphorous acid contamination (< 30%
LOQ) coming from sample preparation is found.
Remarks :
10 = standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
= Before start of validation / measurements equipment / chemicals should be tested for any 15 residues of phosphorous acid.
= If some contamination is observed, see if the use of special HPLC vials (e.g. polypropylene vials, Agilent, art. 5182-0567) can be helpful to reduce the background for phosphorous acid.
20 Assessment of different LC conditions :
All recovery samples were also analysed using different LC conditions. The only modification was the mobile phase.
LC conditions Original Substitute Isocratic mode: 55 / 45 (v/v) Isocratic mode: 35 / 65 (v/v) Change in the mobile phase methanol + 2% HCOOH / methanol / water + 2% HCOOH
composition water + 2% HCOOH
from 3.1 to 4.1 min for phosphorous about 3.2 min for phosphorous Retention times acid and 3.9 to 5.3 min for fosetyl- acid and 5.2 min for fosetyl-Al Al Complete original LC conditions are indicated in 2.3.1 .
The results are presented in Table 27.
Table 27: Summa of the results obtained with substitute LC conditions Calibration curve Test LC
Compound Standards in pure Matrix matched system conditions solvent standards Drinking water original (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
LOQ : OK
original (LOQ and 10LOQ) : OK
H3P03 10LOQ : No substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
original (LOQ and 10LOQ) : OK (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : No Surface water LOQ : No original (LOQ and 10LOQ): OK
10LOQ : OK
LOQ : No substitute (LOQ and 10LOQ) ; OK
10LOQ : OK
"OK" means that the results comply with European requirements.
"No" means that the results do not comply with European requirements.
The column "Standards in pure solvent" is given as information.
When matrix matched standards are used, the different experiments done showed that for surface water the validation failed only for fosetyl-Al at LOQ and 10LOQ if substitute LC
conditions are used. For drinking water, no problem was observed.
For drinking water, the method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996) at 0.1 pg/L and ten times this limit for fosetyl-Al and phosphorous acid, only when matrix matched standards were used, independently of LC
conditions tested.
For surface water, the method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996) at 0.1 pg/L and ten times this limit for fosetyl-Al and phosphorous acid, only when matrix matched standards were used, depending on LC
conditions tested (notably for fosetyl-Al).
5. Variant method A variant method was also validated on drinking water and surface water. The sample preparation of the main method was strongly simplified by the suppression of the concentration step and all recovery samples were analysed in the HPLC and detection conditions given in 2.3.1 and 2.3.2. before the concentration step.
A flow chart of the variant method is given in Appendix 8.
A summary of the results is given in Table 28 and the detailed recovery results obtained are listed in Appendix 7.
Table 28: Summar of the results obtained with variant method Calibration curve Test LC
Compound Standards in pure Matrix matched system conditions solvent standards originai (LOQ and 10LOQ) : OK (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
Drinking water LOQ : No LOQ : No original 10LOQ : OK 10LOQ : OK
LOQ : No substitute (LOQ and 10LOQ) : No 10LOQ : OK
original (LOQ and 10LOQ) : OK (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : OK (LOQand IOLOQ): OK
Surface water LOQ : No LOQ : No original 10LOQ : OK 10LOQ : OK
i-13P03 LOQ : No LOQ : No substitute 10LOQ : OK 10LOQ : OK
"OK" means that the results comply with European requirements.
"No" means that the results do not comply with European requirements.
The column "Standards in pure solvent" is given as information.
Remark : to quantify non concentrated water samples, it is necessary to adapt standards solutions concentrations. As phosphorous acid is not sensitive enough, this method does not allow its determination at the limit of quantification of 0.1 pg/L.
The variant method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996), for non concentrated drinking water and surface water at 0.1Ng/L
for fosetyl-Al and ten times this limit for fosetyl-Al and at lpg/L for phosphorous acid when matrix matched standards were used, independently of the LC conditions tested.
Regarding to the main method, the sample preparation was greatly simplified and allows to save a lot of time.
Appendix 4 Flow Diagram of Residue Method 00931/M001 Main point : for each set of samples, it is necessary to do a blank reagent where water sample is replaced by H20 milliQ to be sure that no H3P03 contamination (< 306 LOQ) coming from sample preparation is found.
0.6 g of washed AG 50W-X8 resin (in disposable Nalgene bottle PP) +
20.0 g of water sample (using disposable Pasteur Pipette) (Add here using a dilutor 200 pL of the fortifying solution for LOQ recoveries or 200 pL of the fortifying solution for IOLOQ recoveries) ~
Mechanical agitation (10 minutes) at ambient temperature: corresponds to Extract A
~
Pour 5 mL of extract (using a disposable glass pipette) into a weighted disposable glass test tube Evaporation at 60 C under a nitrogen flow to about 0.5 g CAUTION NOT TO GO TO DRYNESS
~
Make-up to I g with water + formic acid 0.5%
(using disposable Pasteur Pipette) .
Sonicat~on :
correspond to Final Extract CL HPLC Measurement with Electrospray MS/MS detection If necessary to dilute the Final Extract due to concentration outside the calibration curve : use final extract of control sample (because matrix matched standards are used for calibration) Appendix 5 Details on LC-MS/MS conditions Comment:
Synchronization Mode: LC Sync Auto-Equilibration: Off Acquisition Duration: 10min1sec Number Of Scans: 455 Periods In File: 1 Acquisition Module: Acquisition Method Software version Analyst 1.4 MS Method Properties:
Period 1:
--------------Scans in Period: 455 Relative Start Time: 0.00 msec Experiments in Period: 1 Period 1 Experiment 1:
----------------------------Scan Type: MRM (MRM) Polarity: Negative Scan Mode: N/A
Ion Source: Turbo Spray Resolution Q1: Unit Resolution Q3: Unit Intensity Thres.:0.00 cps Settling Time: 0.0000 msec MR Pause: 5.0070 msec MCA: No Step Size: 0.00 amu Quantifier transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 78.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -22.00 -22.00 CXP -5.00 -5.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 80.90 200.00 DP -45.00 -45.00 (fosetyl-Al) CE -16.00 -16.00 CXP -1.00 -1.00 Confirmatory transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 62.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -38.00 -38.00 CXP -1.00 -1.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 62.90 300.00 DP -45.00 -45.00 (fosetyl-Al) CE -38.00 -38.00 CXP -5.00 -5.00 Parameter Table (Period 1 Experiment 1):
CAD: 6.00 CUR: 20.00 5 GS1: 40.00 GS2: 60.00 TEM: 600.00 ihe: ON
IS: -4500.00 10 EP -10.00 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Binary Pump 15 Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Dead Volume (pl): 40.0 Maximum Flow Ramp (mI/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 20 Step Table:
Step Total Time(min) Flow Rate(pl/min) A(%) B(%) 0 0.00 200 45.0 55.0 1 10.00 200 45.0 55.0 Left Compressibility: 50.0 25 Right Compressibility: 115.0 Left Dead Volume (pi): 40.0 Right Dead Volume (NI):40.0 Left Stroke Volume (pl): -1.0 Right Stroke Volume (pl): -1.0 30 Left Solvent: A2 (water + 2% formic acid) Right Solvent: B1 (methanol + 2% formic acid) CTC PAL Auto sampler Method Properties :
35 Loop Volumel (pl): 50 Loop Volume2 (pl): 50 Injection Volume (pl): 200.000 Method Description:
Syringe: 250ul 40 Analyst LC-Inj Air Volume (pi) 0 Pre Clean with Solvent 1() 2 Pre Clean with Solvent 2O 1 Pre Clean with Sample () 0 45 Filling Speed (pl/s) 50 Filling Strokes () 0 Inject to LC Vlvl Injection Speed (pl/s) 50 Pre Inject Delay (ms) 500 50 Post Inject Delay (ms) 500 Post Clean with Solvent 1() 3 Post Clean with Solvent 2() 2 Valve Clean with Solvent 1() 2 Valve Clean with Solvent 2() 1 Gas pressure Auto sampler CTC Analytics HTS Pal n 1303 N2 4 bar Peltier rack 10 C
Air as 7.5 bar Loop 50 pL
Air Exhaust gas 4 bar Solvent 1 H20 + 0.5% HCOOH
Solvent 2 MeOH
Oven Agilent G1316A n 1294 Temperature Not used Valco valve Column selector n 1289 n 1290) Ten ports 6 positions 2 positions Not used Not used Pumps Source Probe TurbolonSpray n 1291 Binary pump Agilent 1100 G1312A 1400 psi n 1288 n 1297) Flow 0.2 mL/min Horizontal Position 7 (x axis) A2= H20 + 2% Formic Acid 45 % Vertical Position 7 axis) B1= MeOH + 2% Formic Acid 55 % Ca illar exit 1 mm Isocratic Mass Spectrometer API 4000 Device GLP n 1292 Binary pump Agilent 1100 G1312A Not used n 1296) Flow - Column A = - Precolumn none B = - Column SMAR 68-1 Isocratic mode Thermo Hypercarb 100 x 2.0mm 5 m (ambient tem erature Appendix 6 Results obtained with confirmatory transitions Sample Compound Fortification Level Recovery Material [m9/L] Single Values [%] Mean [%] RSD [ /o]
0.0001 77 75 81 85 12.8 fosetyl-AI 0.001 78 73 86 80 6.7 Drinking Overall Mean and RSD 83 10.2 water 0.0001 62 67 86 79 16.6 _ ............ ...... _...........
............................................... _....
...................................................
_................................... _............. _...................
_._........ _............................ _....... __ ......................... __.................
phosphorous 0.001 78 77 84 86 11.0 acid Overall Mean and RSD 82 13.9 0.0001 96 101 106 107 9.4 ................................. ........ _............ _.........
_............ _. ..........................................................
......................... _.._.................. ...................... .__.
.._............... _........ _..... _. ._......... .................
_._............ fosetyl-Al 0.001 99 100 96 97 2.9 Surface Overall Mean and RSD 102 8.8 water 0.0001 116 108 104 109 4.0 phosphorous .............. _..._ ............... _..........................
..................... ............................. _.................
_...................................... ................. _..... _........
_.... _........ ............................. _........
................................... _........
0.001 100 96 93 93 5.6 acid Overall Mean and RSD 101 9.5 Appendix 7 Results obtained with substitute LC conditions Dinking water Fortification Recoveries Calibration Compound Level Sin le Values lo Mean % RSD [%]
9 [ ] [ l ]
[mg/L]
0.0001 10 10 9 9 9.1 fosetyl-AI 0.001 18 18 17 18 4.7 standards in Overall Mean and RSD 14 34.1 pure solvent 0.0001 35 35 37 36 4.6 .....
......... __ .................. _.... _._.......... _........ _......
.......... __.... ............. _......... _...............
__._...__....................... ---........................ _. .............
_...... ................. ..... ......_............ .__.... _..........
phosphorous acid 0.001 29 28 33 30 6.2 Overall Mean and RSD 33 10.6 0.0001 95 94 85 89 6.3 fosetyl-Al 0.001 96 97 94 97 4.0 matrix matched Overall Mean and RSD 93 6.6 standards 0.0001 93 94 98 96 4.6 ............. _..... _......... ._......................................
.._....... ................... .............................
....................... ............_...... ._.._......................... ...
..... ........_....... _........................ .... .......
_..................._..
phosphorous 0.001 85 81 95 87 5.9 acid Overall Mean and RSD 91 7.2 Surface water Fortification Recoveries Calibration curve Compound Level Single Values % Mean[ lo] RSD [%
]
[mg/L]
0.0001 26 26 30 30 17.5
2.1.3. Reference Item See example 3.
2.1.4. Standard Solutions Stock and standard solutions were stored protected from light in a refrigerator at around 5 C.
35 Stock solutions 0 000 mg/L) Into a 100 mL amber screw-cap flask, weigh accurately between 20 and 50 mg of reference item. Using a burette, add a volume of water to obtain a stock solution of exactly 1000 mg/L. Mix thoroughly until complete dissolution using a magnetic stirrer. Two separate stock solutions must be prepared for each compound. After comparison of these two stock solutions, they are mixed.
Mixture solution Pipette 5 mL of each stock solution using a class "A+" pipette. Pour into a class "A" 50 mL
volumetric flask. Adjust volume with water, cap and mix by shaking (100 mg/L
of each compound).
Fortifying standard solutions By serial dilutions of the mixture solution in water, prepare the fortifying standard solution used for recoveries at 10LOQ level (0.1 mg/L of each compound) and the fortifying standard solution used for recoveries at LOQ level (0.01 mg/L of each compound).
Intermediate standard solution By serial dilutions of the mixture solution, prepare the intermediate standard solution at 1.0 mg/L
using water.
Standard solutions in solvent To obtain the standard solutions used for calibration, dilute extemporaneously using a dilutor and water with 0.5% formic acid, the intermediate standard solution to obtain the following concentrations: 0.2, 0.4, 0.5, 0.75, 1, 2, 5, 10 and 20 pg/L.
Matrix matched standard solutions used for calibration The occurrence of matrix effects was monitored and the measurement of both compounds is established using matrix matched standards in both sample materials.
From the intermediate standard solution, the dilutions are the same as preparation of standard solutions in solvent, except the dilution mixture which is the final extract of a control sample.
Remarks :
= 20 to 25 mL of final extract are necessary to make all dilutions.
= final extracts of control sample could be prepared a day before use and stocked in a refrigerator.
2.1.5. Stability of the standard solutions The stock solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 9 months and a half.
2.2. Residue Analytical Methodology Some modifications compared to the original analytical method were introduced.
The method modification 00931/M001 presented in this report was validated in order to suppress the steps of derivatization and clean up, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00931 from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
= The Limit of Quantification was decreased from 0.001 mg/L for fosetyl-Al and 0.004 mg/L for phosphorous acid in surface water and from 0.002 mg/L for phosphorous acid in drinking water to 0.0001 mg/L for each compound in both sample materials.
= The NaOH treatment was replaced by a resin treatment.
= The derivatization step was supressed.
= The clean-up step with liquid-liquid partition was suppressed.
= The quantification was carried out by LC/MS/MS instead of GC/FPD.
All modifications were included in the description below.
A flow chart of the method is given in Appendix 1.
Note : during analysis, for each sample set, it is necessary to do a blank reagent where water sample is replaced by Milli Q water to be sure that no phosphorous acid contamination (< 30%
LOQ) coming from sample preparation is found.
Remark : standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
For recovery experiments, samples are fortified by adding the appropriate standard solution to the sample material after weighing and before shaking.
Preparation of the cationic resin :
15. Weigh about 25 g of AG 50W-X8 resin into a 1000 mL polypropylene bottle.
16. Add about 500 mL of water.
17. Shake using a rotary shaker for about 10 minutes.
18. Discard the supernatant water.
19. Do steps 2 to 4 a second time.
20. Do steps 2 to 4 a third time.
21. Filtrate residual water and resin through two GF/A filters put in a polypropylene funnel and previously rinsed with water.
Remark: resin is prepared either just before use or in advance, stored at ambient temperature and re-hydrated just before use.
Caution: phosphorous acid interferences could be observed if the resin is not washed as described above.
Samples preparation :
1. Weigh 0.6 g of AG 50W-X8 resin previously washed into a 125 mL
polypropylene bottle.
2. Using disposable Pasteur pipette, weigh 20.0 g of homogeneous sample material into the bottle.
Note: weight of the sample is used for residue calculation, addressed as variable Wwater 3. Shake the sample using a rotary shaker for 10 minutes. This is the Extract A.
Note: The weight of Extract A is used for residue calculation, addressed as variable WExtraCc In this case, there was no extraction: no solvent was added to water sample;
it was just a resin treatment, so WExtract = Wwater = 20 g 4. Using a disposable glass pipette, transfer an aliquot of 5 mL of supernatant into a test tube previously weighted.
Note: The volume of aliquot is used for residue calculation, addressed as variable VAUqUOt ( Instead of transferring 5 mL, this aliquot could also be done by weighing 5 g= WAi;qõot 5. Evaporate under a nitrogen flow using a sample concentrator at a temperature of about 60 C to approximately 0.5 g. Caution not to evaporate to dryness.
6. Using disposable pipette, make-up to 1.0 g with acidified water with formic acid 0.5 %.
Note: the concentration of formic acid in acidified water used in step 6 is a critical parameter: it has an important action on the H3P03 peak shape obtained in LC.
The increase from 0.5% to 2% of formic acid in acidified water can give a very large H3P03 peak, and accordingly a loss of sensitivity.
7. Sonicate for about 5 minutes. This is the Final Extract.
Note: weight of Final Extract is used for residue calculation, addressed as variable WEnd 8. Proceed to LC/MS/MS measurement, Chapter 2.3.
Note: if it is necessary to dilute the Final Extract due to a concentration outside the calibration curve: use final extract of control sample because matrix matched standards are used for calibration.
2.3. Analysis and Instrument Conditions The final extracts are injected into a high performance liquid chromatograph and detected by tandem mass spectrometry with electrospray ionisation.
The quantification is carried out by external standardisation using matrix matched standards.
Exemplary LC/MS/MS conditions that were used in the course of this method validation are listed in chapters 2.3.1 and 2.3.2. These conditions are given as a guidance and may have to be adapted for other HPLC-MS/MS systems 2.3.1. HPLC Conditions Instrument: Binary pump Agilent 1100 Auto sampler: CTC Analytics HTS PAL
Column: Hypercarb, 100 x 2.0 mm, 5 pm Precolumn: none Injection Volume: 50 pL
Column temperature: ambient (about 25 C) Mobile Phase:
Isocratic mode: 55 / 45 (v/v) Methanol + 2% formic acid / water + 2% formic acid Flow (Column): 200 pL/min Retention Times: from 3.1 to 4.1 min for phosphorous acid and from 3.9 to 5.3 min for fosetyl-Al.
Remarks :
= Retention times in concentrated samples are lightly shorter than in solvent (about 0.2 min in surface water and 0.5 min in drinking water).
= It is necessary to wait about 2 hours the stabilisation of the HPLC system before injecting.
During a samples set, a light drift of retention time of both compounds can be observed.
= Hypercarb precolumn must not be used.
= Depending of the phase batch of Hypercarb column, the percentage of formic acid in the mobile phase could be adapted to improve peaks shape (from 0.5% to 2%).
2.3.2. MS/MS Conditions See example 3.
2.3.3. Confirmatory transitions See example 3.
Note : all recovery samples were also analysed using confirmatory transitions.
The results are given in Appendix 6.
2.4. Linearity of the Detector The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.2 and 20 pg/L.
Table 16: Standard concentrations prepared for the determination of detector linearity. The concentration corresponding to the LOQ is printed in the third column of the table.
HPLC-MS/MS Standard Concentrations [pg/L]
fosetyl-Al 0.2 0.4 0.5 0.75 1 2 5 10 20 phosphorous acid 0.2 0.4 0.5 0.75 1 2 5 10 20 2.5. Storage Stability of Extracts 5 The stability of sample extracts containing fosetyl-Al and phosphorous acid was not determined in this study.
2.6. Calculation 2.6.1. Calculation of Residues Evaluation in this case is performed according to the external standardisation using matrix matched standards.
During the analysis of each set of samples, the 9 standard solutions mentioned in Table 16 are injected once. Standards should be interspersed with samples to compensate for any minor change in instrument response.
For each compound, the peak area is plotted versus the concentration in order to establish a calibration curve obtained by linear regression weighting 1/x with least squares method.
The corresponding model to determine the concentration in final extracts is calculated using the Analyst Software (Version 1.4).
Each final extract is injected once using the same conditions as previously described for the standard solutions.
Using the predicting mathematical model previously established, the final concentration in pg/L
of each compound is determined for each injection.
For each compound, the amount of residue R, expressed in mg/L is calculated, using the following formula :
R C X VEnd X VExtract =
1000 x VWater x VAl;aõot where: R : Determined amount of residue of fosetyl-Al or phosphorous acid in mg/L
C : Concentration of fosetyl-Al or phosphorous acid found in the final extract in Ng/L
VEnd : Volume of the final extract in mL, considering that : VE,d = WE,d x Density -1 where WEnd = weight of the final extract in g, here I g and Density -1 = 1 mL/g (*) VExtract : Volume of the extract A in mL, considering that : VE~tract =
WExtract x Density -1 where WExtract = weight of the extract A in g, here 20 g and Density ~= 1 mL/g (*).
In this case, there was no extraction: no solvent was added to water sample;
it was just a resin treatment, so WExtraot =Wwater = 20 g Vwater : Volume of the anal tical sam le in mL, considering that : Vwater =
Wwater x Density Y p where Wwater = weight of the water in g, here 20 g and Density ~= 1 mL/g (*) VAi;qõot : Aliquot (of extract A) used before evaporation in mL, here1 5 mL
If the aliquot has been weighed, VAliquot = WAUquot x Density where WAi;quot = weight of the aliquot in g, here 5 g and Density ~= 1 mL/g (*) Remarks (*) :
= The density of all liquid samples (water, extracts) is considered equal to 1 independently to room temperature. This allows to convert weight of liquid samples into volume.
= In order to express phosphorous acid in fosetyl-Al equivalent, the ratio of the molecular weight must be used :
354.1 g/mol ~ 0 Ratio = =1.44 (82.0 x 3) g/mol because 1 mole fosetyl-Al (354.1 g) gives 3 moles of phosphorous acid.
2.6.2. Calculation of Recovery Rates The concentration of each compound in pg/L is determined for the recovery sample according to 2.6.1.
The percent recovery rate is then calculated as follows :
Cx100 Rec =
A
where: Rec : Recovered amount found in fortified sample in %
C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in pg/L
A : Fortified amount of fosetyl-Al or phosphorous acid in Ng/L
2.6.3. Calculation of Relative Standard Deviation (RSD) The RSD is calculated as follows :
RSD (%) = S.D. / Mean Recovery x 100 %
E (R; - Rm)2 Ri : recovery S.D. _ [ VVZ
Rm : mean recovery n- 1 n: number of recoveries 3. Results and Discussion 3.1. Specificity and Selectivity The method allows the determination of fosetyl-Al and its metabolite (phosphorous acid) in drinking water and surface water samples.
The specificity of the method resulted from the HPLC separation in combination with the very selective MS/MS detection.
3.2. Apparent residues in Control Samples Two control samples were analysed for each sample material. The origin of the control materials used is listed in Table 17.
Table 17: Origin of untreated control samples Test system Origin Drinking water BCS - CRLD - Tap water from lab D221 - Lyon - France Surface water St Agnan en Vercors - France Some characteristics of surface water are recorded in Table 18.
Table 18: Characteristics of surface water date of pH Ca++ clay particles total organic conductivity collect at 16.5 C (mg/L) (mg/L) carbon (TOC) (pS/cm) (yyyy/mm/dd) (mg/L) (NF T 90-008) (potentiometric (NF EN 872) (NF EN 1484) (NF EN 27 888) detection) 2005/03/27 8.1 88 < 2 1.00 400 These characteristics were determined by :
Cemagref Division qualite des eaux et prevention des pollutions Groupement de Lyon 3 bis quai Chauveau 69336 Lyon cedex 09 - France A residue level estimation in control samples was performed. The results are listed in Table 19.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.00003 mg/L.
Table 19: Apparent residues in untreated control samples for fosetyl-Al and phosphorous acid Sample Origin LOQ Apparent residues Material [mg/L] [mg/L]
fosetyl-AI phospho- fosetyl-Al phospho-rous acid rous acid Drinking BCS - CRLD - Tap water water from lab D221 - Lyon - 0.0001 0.0001 < 30% LOQ < 30 / LOQ
France Surface St Agnan en Vercors -0.0001 0.0001 water < 30% LOQ < 30% LOQ
France 3.3. Limit of detection Control sample fortified at 0.00005 mg/L were analysed to test the limit of detection of fosetyl-Al and phosphorous acid. The results are given in Table 20.
Table 20: Recovery rate obtained for fosetyl-Al and phosphorous acid at 0.05 pg/L fortification level Sample Material Fortification level Recovery [mg/L] [%]
fosetyl-Al phosphorous fosetyl-Al phosphorous acid acid Drinking water 0.00005 0.00005 89 75 Surface water 0.00005 0.00005 106 95 3.4. Linearity of the Detectors and Matrix Effects The linearity of the detector used was tested for fosetyl-A( and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.2 and 20 pg/L.
Experimental details can be found in Chapter 2.4.
In each chromatogram, the measured peak area of fosetyl-Al or phosphorous acid is plotted versus the corresponding concentration of respectively fosetyl-Al or phosphorous acid contained in each standard solution, in order to obtain calibration curve of the form :
y = ax + b (1 /x weighting) where : y = peak area, x = concentration in injected standard solution The results of the determination of detector response for LC/MS/MS are summarised in Table 21.
Table 21: Summary of the determination of detector linearity for LC/MS/MS.
phosphorous Detection Parameter fosetyl-Al acid LC/MS/MS Linear range [Ng/L] 0.2 - 20 0.2 - 20 No. of concentrations 9 9 ............. I............. _................. ...._......
_........................................ _- ....................
_.,.......... _................. _............. ..............................
---.................................. u........ ........ ..
....................... __..............................................
No. of injections 1 1 ....................... _........... . .......................................
_.............. _.... _......................
_.................................. _..... _........ _..... ......
_........... _................. _....... _...---......... _. ...
........................................... ..............................
_.......
Model 1/x weighted 1/x weighted linear regression linear regression ................................................ _...---..................
................... .........................................................
. ........................ ........... ................................ ....
............... ._._................. .....
................................... _.................... ....................
Correlation coefficient (R) > 0.9993 > 0.9991 for standards prepared in solvent Correlation coefficient (R) > 0.9981 > 0.9990 for matrix matched standards An excellent linear correlation between the injected amount of the analytes and the detector responses of LC/MS/MS was observed for standards in the range of 0.2 to 20 pg/L for both compounds, using either standards prepared in solvent or matrix matched standards.
5 The occurrence of matrix effects was monitored. The results are shown in Table 22 and table 23.
Table 22: Matrix effect evaluation for fosetyl-Al.
FL : Fortification Level Measurement using Number Sample Material FL of Values Standards in pure Matrix matched [mg/L] solvent standards (n) Mean [%] RSD [%] Mean [%] RSD [%]
Drinking water 0.0001 5 25 17.0 86 12.2 0.001 5 33 7.0 82 6.5 Surface water 0.0004 5 97 7.9 107 6.4 0.001 5 103 3.4 96 3.3 Table 23: Matrix effect evaluation for phosphorous acid 10 FL : Fortification Level Measurement using Number Sample Material FL of Values Standards in pure Matrix matched [mg/L] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
Drinking water 0.0001 5 80 3.3 76 5.7 0.001 5 64 11.3 88 11.9 Surface water 0.0001 5 123 4.2 109 4.1 0.001 5 101 4.6 93 4.6 In drinking water, the measurement of fosetyl-Al must be established using matrix matched standards. The results obtained with standards in pure solvent for phosphorous acid in both sample materials do not always comply with European requirements. So the measurement of both compounds in drinking water and surface water is established using matrix matched standards.
3.5. Limit of Quantification and Recovery Experiments The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of s 20% could be obtained.
The LOQ was set at 0.0001 mg/L for each compounds in drinking water and surface water.
To validate the method for these matrices, samples were fortified with a defined amount of fosetyl-Al and phosphorous acid prior to analysis.
3.6. Recovery Rates The detailed recovery results obtained are listed in Table 24 and table 25.
Table 24: Recovery rates obtained for fosetyl-Al, RSD: relative standard deviation Fortification Level Recovery of fosetyl-Al Sample Material [mg/L] Single Values [%] Mean [%] RSD [%]
Drinking water 0.0001 76 76 87 86 12.2 ................................ ._.._................... _.......... _.....
_.. ._........................................................... ..........
...........................................................
..............................................
...............................................
0.001 78 75 87 82 6.5 Overall Mean and RSD 84 9.7 Surface water 0.0001 100 103 107 107 6.4 ......... ._.......... ... ...................................... ._ .............. .......... ............. _.................................
_................. ....................................... ................
.............................................
...............................................
0.001 98 100 96 96 3.3 F Overall Mean and RSD 101 7.5 Table 25: Recovery rates obtained for Phosphorous acid, RSD: relative standard deviation Fortification Level Recovery of Phosphorous acid Sample Material [mg/L] Single Values [%] Mean [%] RSD [%]
Drinking water 0.0001 72 72 74 76 5.7 0.001 80 76 89 88 11.9 Overall Mean and RSD 82 12.4 Surface water 0.0001 109 106 106 109 4.1 0.001 97 98 94 93 4.6 Overall Mean and RSD 101 9.3 The obtained recovery rates are summarised below in Table 26.
In total 20 recovery rates were determined for each compound.
The single recovery rates were in the range of 75 to 118 % for fosetyl-Al and of 72 to 117 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 89 to 96 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 93% and of 91 to 93 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 92 %.
The relative standard deviations (RSD) for the single fortification levels ranged from 9.6 to 14.3 % for fosetyl-Al and from 8.8 to 19.8 % for phosphorous acid (n=10).
The overall RSD values per sample material were between 7.5 and 9.7 % for fosetyl-Al and 9.3 and 12.4 % for phosphorous acid (n=10). The RSD value across all samples was 12.7 % for fosetyl-Al and 15.0 % for phosphorous acid (n=20).
Table 26: Summary of the recovery data for the determination of accuracy and repeatability;
RSD: relative standard deviation Parameter Phospho-fosetyl-AI
rous acid Accuracy Single recoveries [%] 75 - 118 72 - 117 Mean recoveries per fortification level [ lo] 89 - 96 91 - 93 Mean recoveries per sample material [%] 84 - 101 82 - 101 Overall mean [%] 93 92 Number of values n 20 20 Repeatability RSD per fortification level [%] 9.6 - 14.3 8.8 - 19.8 RSD per sample material [%] 7.5 - 9.7 9.3 - 12.4 Overall RSD [%] 12.7 15.0 3.7. Storage Stability of Extracts The stability of sample extracts containing fosetyl-Al and phosphorous acid was not determined in this study.
4. Evaluation and Discussion The presented residue analytical method modification 00931/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in drinking water and surface water by LC/MS/MS.
The sample material is treated with a cationic resin and then concentrated.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation.
The quantification was done by an external standardisation in matrix matched standards.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at respective concentrations between 0.1 and 5 pg/L and 1 and 50 pg/L, except for wheat samples between 0.31 and 8.3 pg/L and 3.1 and 83 pg/L. The detector response was linear in these ranges.
The occurrence of matrix effects was monitored.
In all the sample materials, the measurement of phosphorous acid must be established using matrix matched standards. So the measurement of both compounds is established using matrix matched standards.
The apparent residues for all control samples were below 30% of the LOQ for each compound, i.e. < 0.003 mg/kg of fosetyl-Al and < 0.03 mg/kg of phosphorous acid.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of <_ 20% could be obtained. The LOQ was set at 0.01 mg/kg for fosetyl-Al and at 0.1 mg/kg for phosphorous acid in grape (whole fruit), orange (whole fruit), lettuce (head), cucumber (whole fruit), avocado (whole fruit), and wheat (grain).
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 69 to 114 % for fosetyl-Al and of 65 to 113 % for phosphorous acid. The mean recovery rates per fortification level were in the range of 93 to 97 % for fosetyl-Al with an overall recovery rate over all sample materials and fortification levels of 95% and of 86 to 97 % for phosphorous acid with an overall recovery rate over all sample materials and fortification levels of 91 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
the relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The relative standard deviations (RSD) for the single fortification levels ranged from 7.6 to 12.3 % for fosetyl-Al and from 9.5 to 14.9 % for phosphorous acid (n=30).
The overall RSD values per sample material were between 2.1 and 10.9 % for fosetyl-Al and 6.0 and 17.8 % for phosphorous acid (n=10). The RSD value across all samples was 10.2 % for fosetyl-Al and 13.7 % for phosphorous acid (n=60). All RSD values were well below 20%, so that the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue 5 analytical methods, so this method modification has been validated successfully.
Note : during analysis, for each sample set, it is necessary to do a blank reagent where water sample is replaced by Milli Q water to be sure that no phosphorous acid contamination (< 30%
LOQ) coming from sample preparation is found.
Remarks :
10 = standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
= Before start of validation / measurements equipment / chemicals should be tested for any 15 residues of phosphorous acid.
= If some contamination is observed, see if the use of special HPLC vials (e.g. polypropylene vials, Agilent, art. 5182-0567) can be helpful to reduce the background for phosphorous acid.
20 Assessment of different LC conditions :
All recovery samples were also analysed using different LC conditions. The only modification was the mobile phase.
LC conditions Original Substitute Isocratic mode: 55 / 45 (v/v) Isocratic mode: 35 / 65 (v/v) Change in the mobile phase methanol + 2% HCOOH / methanol / water + 2% HCOOH
composition water + 2% HCOOH
from 3.1 to 4.1 min for phosphorous about 3.2 min for phosphorous Retention times acid and 3.9 to 5.3 min for fosetyl- acid and 5.2 min for fosetyl-Al Al Complete original LC conditions are indicated in 2.3.1 .
The results are presented in Table 27.
Table 27: Summa of the results obtained with substitute LC conditions Calibration curve Test LC
Compound Standards in pure Matrix matched system conditions solvent standards Drinking water original (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
LOQ : OK
original (LOQ and 10LOQ) : OK
H3P03 10LOQ : No substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
original (LOQ and 10LOQ) : OK (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : No Surface water LOQ : No original (LOQ and 10LOQ): OK
10LOQ : OK
LOQ : No substitute (LOQ and 10LOQ) ; OK
10LOQ : OK
"OK" means that the results comply with European requirements.
"No" means that the results do not comply with European requirements.
The column "Standards in pure solvent" is given as information.
When matrix matched standards are used, the different experiments done showed that for surface water the validation failed only for fosetyl-Al at LOQ and 10LOQ if substitute LC
conditions are used. For drinking water, no problem was observed.
For drinking water, the method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996) at 0.1 pg/L and ten times this limit for fosetyl-Al and phosphorous acid, only when matrix matched standards were used, independently of LC
conditions tested.
For surface water, the method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996) at 0.1 pg/L and ten times this limit for fosetyl-Al and phosphorous acid, only when matrix matched standards were used, depending on LC
conditions tested (notably for fosetyl-Al).
5. Variant method A variant method was also validated on drinking water and surface water. The sample preparation of the main method was strongly simplified by the suppression of the concentration step and all recovery samples were analysed in the HPLC and detection conditions given in 2.3.1 and 2.3.2. before the concentration step.
A flow chart of the variant method is given in Appendix 8.
A summary of the results is given in Table 28 and the detailed recovery results obtained are listed in Appendix 7.
Table 28: Summar of the results obtained with variant method Calibration curve Test LC
Compound Standards in pure Matrix matched system conditions solvent standards originai (LOQ and 10LOQ) : OK (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : No (LOQ and 10LOQ) : OK
Drinking water LOQ : No LOQ : No original 10LOQ : OK 10LOQ : OK
LOQ : No substitute (LOQ and 10LOQ) : No 10LOQ : OK
original (LOQ and 10LOQ) : OK (LOQ and 10LOQ) : OK
fosetyl-Al substitute (LOQ and 10LOQ) : OK (LOQand IOLOQ): OK
Surface water LOQ : No LOQ : No original 10LOQ : OK 10LOQ : OK
i-13P03 LOQ : No LOQ : No substitute 10LOQ : OK 10LOQ : OK
"OK" means that the results comply with European requirements.
"No" means that the results do not comply with European requirements.
The column "Standards in pure solvent" is given as information.
Remark : to quantify non concentrated water samples, it is necessary to adapt standards solutions concentrations. As phosphorous acid is not sensitive enough, this method does not allow its determination at the limit of quantification of 0.1 pg/L.
The variant method was successfully validated, according to the European requirements (96/46/EC of 16th July 1996), for non concentrated drinking water and surface water at 0.1Ng/L
for fosetyl-Al and ten times this limit for fosetyl-Al and at lpg/L for phosphorous acid when matrix matched standards were used, independently of the LC conditions tested.
Regarding to the main method, the sample preparation was greatly simplified and allows to save a lot of time.
Appendix 4 Flow Diagram of Residue Method 00931/M001 Main point : for each set of samples, it is necessary to do a blank reagent where water sample is replaced by H20 milliQ to be sure that no H3P03 contamination (< 306 LOQ) coming from sample preparation is found.
0.6 g of washed AG 50W-X8 resin (in disposable Nalgene bottle PP) +
20.0 g of water sample (using disposable Pasteur Pipette) (Add here using a dilutor 200 pL of the fortifying solution for LOQ recoveries or 200 pL of the fortifying solution for IOLOQ recoveries) ~
Mechanical agitation (10 minutes) at ambient temperature: corresponds to Extract A
~
Pour 5 mL of extract (using a disposable glass pipette) into a weighted disposable glass test tube Evaporation at 60 C under a nitrogen flow to about 0.5 g CAUTION NOT TO GO TO DRYNESS
~
Make-up to I g with water + formic acid 0.5%
(using disposable Pasteur Pipette) .
Sonicat~on :
correspond to Final Extract CL HPLC Measurement with Electrospray MS/MS detection If necessary to dilute the Final Extract due to concentration outside the calibration curve : use final extract of control sample (because matrix matched standards are used for calibration) Appendix 5 Details on LC-MS/MS conditions Comment:
Synchronization Mode: LC Sync Auto-Equilibration: Off Acquisition Duration: 10min1sec Number Of Scans: 455 Periods In File: 1 Acquisition Module: Acquisition Method Software version Analyst 1.4 MS Method Properties:
Period 1:
--------------Scans in Period: 455 Relative Start Time: 0.00 msec Experiments in Period: 1 Period 1 Experiment 1:
----------------------------Scan Type: MRM (MRM) Polarity: Negative Scan Mode: N/A
Ion Source: Turbo Spray Resolution Q1: Unit Resolution Q3: Unit Intensity Thres.:0.00 cps Settling Time: 0.0000 msec MR Pause: 5.0070 msec MCA: No Step Size: 0.00 amu Quantifier transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 78.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -22.00 -22.00 CXP -5.00 -5.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 80.90 200.00 DP -45.00 -45.00 (fosetyl-Al) CE -16.00 -16.00 CXP -1.00 -1.00 Confirmatory transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 62.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -38.00 -38.00 CXP -1.00 -1.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 62.90 300.00 DP -45.00 -45.00 (fosetyl-Al) CE -38.00 -38.00 CXP -5.00 -5.00 Parameter Table (Period 1 Experiment 1):
CAD: 6.00 CUR: 20.00 5 GS1: 40.00 GS2: 60.00 TEM: 600.00 ihe: ON
IS: -4500.00 10 EP -10.00 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Binary Pump 15 Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Dead Volume (pl): 40.0 Maximum Flow Ramp (mI/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 20 Step Table:
Step Total Time(min) Flow Rate(pl/min) A(%) B(%) 0 0.00 200 45.0 55.0 1 10.00 200 45.0 55.0 Left Compressibility: 50.0 25 Right Compressibility: 115.0 Left Dead Volume (pi): 40.0 Right Dead Volume (NI):40.0 Left Stroke Volume (pl): -1.0 Right Stroke Volume (pl): -1.0 30 Left Solvent: A2 (water + 2% formic acid) Right Solvent: B1 (methanol + 2% formic acid) CTC PAL Auto sampler Method Properties :
35 Loop Volumel (pl): 50 Loop Volume2 (pl): 50 Injection Volume (pl): 200.000 Method Description:
Syringe: 250ul 40 Analyst LC-Inj Air Volume (pi) 0 Pre Clean with Solvent 1() 2 Pre Clean with Solvent 2O 1 Pre Clean with Sample () 0 45 Filling Speed (pl/s) 50 Filling Strokes () 0 Inject to LC Vlvl Injection Speed (pl/s) 50 Pre Inject Delay (ms) 500 50 Post Inject Delay (ms) 500 Post Clean with Solvent 1() 3 Post Clean with Solvent 2() 2 Valve Clean with Solvent 1() 2 Valve Clean with Solvent 2() 1 Gas pressure Auto sampler CTC Analytics HTS Pal n 1303 N2 4 bar Peltier rack 10 C
Air as 7.5 bar Loop 50 pL
Air Exhaust gas 4 bar Solvent 1 H20 + 0.5% HCOOH
Solvent 2 MeOH
Oven Agilent G1316A n 1294 Temperature Not used Valco valve Column selector n 1289 n 1290) Ten ports 6 positions 2 positions Not used Not used Pumps Source Probe TurbolonSpray n 1291 Binary pump Agilent 1100 G1312A 1400 psi n 1288 n 1297) Flow 0.2 mL/min Horizontal Position 7 (x axis) A2= H20 + 2% Formic Acid 45 % Vertical Position 7 axis) B1= MeOH + 2% Formic Acid 55 % Ca illar exit 1 mm Isocratic Mass Spectrometer API 4000 Device GLP n 1292 Binary pump Agilent 1100 G1312A Not used n 1296) Flow - Column A = - Precolumn none B = - Column SMAR 68-1 Isocratic mode Thermo Hypercarb 100 x 2.0mm 5 m (ambient tem erature Appendix 6 Results obtained with confirmatory transitions Sample Compound Fortification Level Recovery Material [m9/L] Single Values [%] Mean [%] RSD [ /o]
0.0001 77 75 81 85 12.8 fosetyl-AI 0.001 78 73 86 80 6.7 Drinking Overall Mean and RSD 83 10.2 water 0.0001 62 67 86 79 16.6 _ ............ ...... _...........
............................................... _....
...................................................
_................................... _............. _...................
_._........ _............................ _....... __ ......................... __.................
phosphorous 0.001 78 77 84 86 11.0 acid Overall Mean and RSD 82 13.9 0.0001 96 101 106 107 9.4 ................................. ........ _............ _.........
_............ _. ..........................................................
......................... _.._.................. ...................... .__.
.._............... _........ _..... _. ._......... .................
_._............ fosetyl-Al 0.001 99 100 96 97 2.9 Surface Overall Mean and RSD 102 8.8 water 0.0001 116 108 104 109 4.0 phosphorous .............. _..._ ............... _..........................
..................... ............................. _.................
_...................................... ................. _..... _........
_.... _........ ............................. _........
................................... _........
0.001 100 96 93 93 5.6 acid Overall Mean and RSD 101 9.5 Appendix 7 Results obtained with substitute LC conditions Dinking water Fortification Recoveries Calibration Compound Level Sin le Values lo Mean % RSD [%]
9 [ ] [ l ]
[mg/L]
0.0001 10 10 9 9 9.1 fosetyl-AI 0.001 18 18 17 18 4.7 standards in Overall Mean and RSD 14 34.1 pure solvent 0.0001 35 35 37 36 4.6 .....
......... __ .................. _.... _._.......... _........ _......
.......... __.... ............. _......... _...............
__._...__....................... ---........................ _. .............
_...... ................. ..... ......_............ .__.... _..........
phosphorous acid 0.001 29 28 33 30 6.2 Overall Mean and RSD 33 10.6 0.0001 95 94 85 89 6.3 fosetyl-Al 0.001 96 97 94 97 4.0 matrix matched Overall Mean and RSD 93 6.6 standards 0.0001 93 94 98 96 4.6 ............. _..... _......... ._......................................
.._....... ................... .............................
....................... ............_...... ._.._......................... ...
..... ........_....... _........................ .... .......
_..................._..
phosphorous 0.001 85 81 95 87 5.9 acid Overall Mean and RSD 91 7.2 Surface water Fortification Recoveries Calibration curve Compound Level Single Values % Mean[ lo] RSD [%
]
[mg/L]
0.0001 26 26 30 30 17.5
31 39 ....................... .............................. _.... _.._........
.......... .....................
...................................................
_............................ _._............... . .. . .......
.................................. ................... .......................
_.
fosetyl-Al 0.001 45 59 71 59 15.7 standards in Overall Mean and RSD 45 37.1 pure solvent 0.0001 51 63 64 60 9.2 ............................................................. ..... _.........
--.......... __..... ................ .................... .................
_......................................... ........ _....... .....
................. ...... ..... _.......... ....... _.............
phosphorous 0.001 69 73 71 70 3.5 acid Overall Mean and RSD 65 9.8 0.0001 103 102 111 112 10.1 ................. .......... ........................... _...............
........................
............................................................ ...........
.................... ----............ .... .......................... _......
_.... ._...........................................
fosetyl-Al 0.001 98 127 151 126 14.9 matrix matched Overall Mean and RSD 119 13.8 standards 0.0001 89 106 109 103 8.2 _........
............. .......... _............ _........ .......................
._............................ ....................
.......................................... __..........................
........ ...................... _........ _._.... .... ....................
_......
phosphorous 0.001 105 110 108 105 3.6 acid Overall Mean and RSD 104 6.0 Appendix 8 Flow chart of variant method Main point : for each set of samples, it is necessary to do a blank reagent where water sample is replaced by H20 milliQ to be sure that no H3P03 contamination (< 30% LOQ) coming from sample preparation is found.
0.6 g of washed AG 50W-X6 resin (in disposable Nalgene bottle PP) +
20.0 g of water sample (using disposable Pasteur Pipette) (Add here using a dilutor 200 NL of the fortifying solution for LOQ recoveries or 200 NL of the fortifying solution for IOLOQ recoveries) Mechanical agitation (10 minutes) at ambient temperature :
Extract A corresponds to Fil7al Extract HPLC Measurement with Electrospray MS/MS detection If necessary to dilute the Final Extract due to concentration outside the calibration curve : use final extract of control sample s (because matrix matched standards are used for calibration) Appendix 9 Results obtained with variant method Drinking water Fortification Recoveries Calibration Compound Level Single curve Values [%] Mean [%] RSD [%]
[mg/L]
0.0001 99 97 99 97 2.1 ..................................... _........._..__.... . ....... .........
....
_............_.................................................................
............................................
............................................. ..._........... _............
_.__....._..
fosetyl-Al 0.001 101 98 91 96 3.9 standards in pure solvent Overall Mean and RSD 97 3.0 0.0001 no result ............................................... ........ __.......... .......
............. ........ ...............................................
_.._..... .. . ...............................
............................................................................
...... _.......
phosphorous 0.001 105 100 101 101 2.0 acid 101 100 Overall Mean and RSD 101 2.0 0.0001 106 104 106 104 2.0 .............................................................. _...........
.................... ................ ..................................
......... _..__............................ _... ...............
..........._....._................... ............
_................................
fosetyl-Al 0.001 101 98 92 96 3.5 matrix 95 96 matched standards Overall Mean and RSD 100 5.0 0.0001 no result .e ....................................................................
....... ....._..........
_.._..............................................................
.................... _......... ......... _... ......... .....
........_.................... ..... _.... ...... ............................
phosphorous 0.001 98 92 93 94 2.7 acid 93 92 Overall Mean and RSD 94 2.7 Surface water Fortification Recoveries Calibration Compound Level Sin le Values % Mean % RSD [%]
g [ ] [ ] ]
[mg/L]
0.0001 103 87 101 97 7.9 ...
........................................ .... ............................
....... _.......................... _........... _..................... _.....
...... ....... _.. - .._.........---.............. _.............. _.....
_....... _.......... .._........................................
fosetyl-Al 0.001 101 102 98 101 1.7 standards in pure solvent Overall Mean and RSD 99 5.7 0.0001 no result _............. ...... ........... _.......................................
.................... ..................... _..............
_.......................... ..................................................
....... _..................................
_..................................... ..........
phosphorous 0.001 97 97 94 97 2.1 acid 99 99 Overall Mean and RSD 97 2.1 0.0001 104 88 102 98 7.9 .............. ....... .......... ....................... _.................
....... _........... ....................... .... ._...... . _....
........................................................................
.............. ......... _...................
................................... _..........
fosetyl-Al 0.001 101 101 98 100 1.6 matrix 102 99 matched standards Overall Mean and RSD 99 5.4 0.0001 no result ............ ................... _......................................... _ ..................................................................
....................................... __.... _...................
........................................... ..........................
_.................... ....
phosphorous 0.001 93 93 90 93 2.2 acid 95 95 Overall Mean and RSD 93 2.2 Example 5 :
This detailed example concerns the analysis of fosetyl-Al and of phosphorous acid using soil samples. This example is a modification M001 to the Analytical Method 00974 for the determination of residues of fosetyl-Al and its metabolite (Phosphorous acid) in soils.
Data Requirement = EU Council Directive 91/414/EEC amended by Commission Directive 96/46/EC
= European Commission Guidance Document for Generating and Reporting Methods of Analysis in Support of Pre-Registration Data Requirements for Annex II (Part A, Section 4) and Annex III (Part A, Section 5) of Directive 91/414, SANCO/3029/99 = European Commission Guidance Document for Residue Analytical Methods, SANCO/825/00 rev.7 Summary The presented residue analytical method modification 00974/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in soils by LC/MS/MS.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are extracted from the soil samples by shaking with ammonia buffer solution. This extract is then treated with a cationic resin and a final dilution is done before the analysis by LCMSMS. The residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation using standards prepared in pure solvent.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L.
The occurrence of matrix effects was monitored.
The conclusion is that :
- no significant difference is observed when the measurement of fosetyl-Al is established using either standards prepared in solvents, or matrix matched standards ;
- the measurement of phosphorous acid is better (higher mean recoveries and lower RSD found) when it is established using standards prepared in solvents, instead of using matrix matched standards.
For all these reasons, standards prepared in solvents should be used.
The apparent residues for all control samples were below 20 / of the LOQ for each compound, i.e. < 0.01 mg/kg.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of 20% could be obtained.
The LOQ was set at 0.050 mg/kg for each compounds in soils samples.
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 70 to 81 % for fosetyl-Al and of 80 to 98 % for phosphorous acid. All mean recoveries rates were in the range of 70 to 110 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
All RSD were well below 20 %. Thus the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so this method modification has been validated successfully.
1 Introduction Fosetyl-Al is a fungicide.
The method modification 00974/M001 presented in this report was validated in order to suppress the steps of derivatization, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00974 from 0.100 mg/kg to 0.050 mg/kg for fosetyl-Al and phosphorous acid.
Table 29: LOQ and principle of analytical determination Compound Fosetyl-Al Phosphorous acid Determined as Fosetyl-Al Phosphorous acid Calculated as Fosetyl-Al Phosphorous acid Principle of Determination LC/MS/MS LC/MS/MS
LOQi [mg/kg] Soil sample 0.05 0.05 i: e ine as e owes va i a e o i ica ion eve 1.1 Citation of the Original Method Original Method : 00974 Compounds : fosetyl-Al and its metabolite (phosphorous acid) Reason for Modification : =Suppress the steps of derivatization.
i, defined as the lowest validated fortification level =Change analysis and detection modes from GC/FPD
to LC/MS/MS.
=Decrease the LOQ from 0.100 mg/kg to 0.050 mg/kg for fosetyl-Al and phosphorous acid 1.2 Physical and Chemical Properties See example 3.
2 Experimental Section 10 2.1 Materials 2.1.1 Apparatus Standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
15 = Balances :
- accuracy 0.1 mg (analytical standards) (e.g. Mettler AT261 range) - accuracy 0.1 g (samples) (e.g. Mettler PM2000) = Dilutor (e.g. Hamilton MicroLab 1000 plus) = Rotary shaker (e.g. Heidolph REAX 2) 20 = Centrifuge (e.g. Hermle Z513fC) (ex Hettich EBA12) = HPLC (e.g. Binary Pump Agilent 1100) = Autosampler (e.g. CTC Analytics HTC PAL) = Triple Quadrupole HPLC-MS/MS Mass Spectrometer 25 (e.g. Sciex Instruments, API 4000 System) = Column (e.g. Hypercarb, 100 x 2.0 mm, 5pm ) 3.1.2 Reagents and Supplies = Acetone (e.g. Pestipur SDS) 30 = Methanol (e.g. Pestipur SDS) = Formic acid (e.g. Analytical reagent Merck) = Ammonium hydrogen carbonate (e.g. Normapur Merck) = ammonia solution 32% (e.g. Rectapur Merck) = Cationic resin (AG 50W-X8, 20-50 Meshs, hydrogen form) (e.g. Bio Rad) 35 = GF/A filters (125 mm), (e.g. Whatman) = Polypro bottles (1000 mL, wide opening) (e.g. Nalgen) = Polypro bottles (250 mL, wide opening) (e.g. Nalgen) = Polypro bottles (125 mL, wide opening) (e.g. Nalgen) = Polypro bottles (60 mL, wide opening) (e.g. Nalgen) 40 = Polypro funnels (67mm) (e.g. Marylands Plastics) = Conical centrifuge tube (15 mL) (e.g. Merck) = Solvent for dilution : Water with 0.5 % HCOOH
= Mobile phase solvent : Water with 2 % HCOOH
Methanol with 2 % HCOOH
= ammonia buffer solution : pour 500 mL of water in a 1000 mL volumetric flask, add 20 g of ammonium hydrogen carbonate and mix with a magnetic stirrer until complete solubilisation. Add 15 mL of ammonia solution 32% and complete to 1000 mL with water.
2.1.3 Reference Item Only sufficiently characterised and certified item was used as reference item.
The reference item was made available by Bayer CropScience GmbH produkt Analytik, G864, Industriepark Hochst, D-65926 Frankfurt-am-Main, Germany.
Table 30: Reference item data Name of Substance Batch Number Content [%] Date of Expiry fosetyl-Al 12/1080 97.6 February 20, 2006 phosphorous acid 04911 DN 96.2 March 02, 2008 2.1.4 Standard Solutions Stock and standard solutions were stored protected from light in a refrigerator at around 5 C.
Stock solutions (1000 mg/L) Into a 100 mL amber screw-cap flask, weigh accurately between 20 and 50 mg of reference item. Using a burette, add a volume of water to obtain a stock solution of exactly 1000 mg/L. Mix thoroughly until complete dissolution using a magnetic stirrer. Two separate stock solutions must be prepared for each compound. After comparison of these two stock solutions, they are mixed.
Mixture solutions Pipette 5 mL of each stock solution using a class "A+" pipette. Pour into a class "A" 50 mL
volumetric flask. Adjust volume with water, cap and mix by shaking (100 mg/L
of each compound). Two different mixture solutions are prepared.
Fortifying standard solutions By dilution in water of one of the mixture solution, which is also used as fortifying solution for recoveries at 10LOQ level (100 mg/L of each compound), prepare the fortifying standard solution used for recoveries at LOQ level (10 mg/L of each compound).
Intermediate standard solution By serial dilutions of the other mixture solution, prepare the intermediate standard solution at 1.0 mg/L of each compound using water.
Before use, the intermediate solution and the fortifying standard solution used for recoveries at LOQ level are compared to validate their preparation.
Standard solutions in solvent used for calibration To obtain the standard solutions used for calibration, dilute extemporaneously using a dilutor (or in a different way) and water with 0.5% formic acid, the intermediate standard solution to obtain the following concentrations: 0.25, 0.4, 0.5, 1, 2.5, 5, 10 and 25 pg/L.
Matrix matched standard solutions The occurrence of matrix effects was monitored and the measurement of both compounds is established using matrix matched standards in both sample materials.
From the intermediate standard solution, the dilutions are the same as preparation of standard solutions in solvent, except the dilution mixture which is the final extract of a control sample.
Remarks :
= 20 to 25 mL of final extract are necessary to make all dilutions.
= to avoid the use of standard laboratory glass consumable, which could bring some H3P03 contamination, the dilution of the control sample extract B is done by weighing. Using disposable Pasteur pipette weigh 3.0 g of extract B into a 60 mL polypropylene bottle. Using another disposable Pasteur pipette, make-up to 30.0 g with acidified water with formic acid 0.5 % : this is the control sample final extract used as dilution mixture to prepare matrix matched standard solutions.
2.1.5 Stability of the standard solutions The stock solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 9 months and a half.
2.2 Residue Analytical Methodology Some modifications compared to the original analytical method were introduced.
The method modification 00974/M001 presented in this report was validated in order to suppress the steps of derivatization, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00974 from 0.100 mg/kg to 0.050 mg/kg for each compound.
= The Limit of Quantification was decreased from 0.100 mg/kg to 0.050 mg/kg for fosetyl-Al and phosphorous acid.
= The derivatization step was suppressed.
= The quantification was carried out by LC/MS/MS instead of GC/FPD.
All modifications were included in the description below.
A flow chart of the method is given in Appendix 7.
Note : during analysis, for each sample set, it is necessary to do a blank reagent without soil sample to be sure that no phosphorous acid contamination (< 30 lo LOQ) coming from sample preparation is found.
Remark : standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
For recovery experiments, samples are fortified by adding the appropriate standard solution to the sample material after weighing and before shaking.
Preparation of the cationic resin :
1. Weigh about 25 g of AG 50W-X8 resin into a 1000 mL polypropylene bottle.
2. Add about 500 mL of water.
3. Shake using a rotary shaker for about 10 minutes.
4. Discard the supernatant water.
5. Do steps 2 to 4 a second time.
6. Do steps 2 to 4 a third time.
7. Filtrate residual water and resin through two GF/A filters put in a polypropylene funnel and previously rinsed with water.
Remark: resin is prepared either just before use or in advance, stored at ambient temperature and rehydrated just before use.
Caution: phosphorous acid interferences could be observed if the resin is not washed as described above.
Samples preparation :
1. Weigh 20.0 g of homogeneous sample material into a 125 mL polypropylene bottle.
Note: weight of the sample is used for residue calculation, as variable Weight Sample ' 2. Add 30 mL of ammonia buffer solution.
3. Shake the sample using a rotary shaker for 30 minutes at ambient temperature.
4. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
5. Pour about 100 g of acidified water with formic acid 0.5 % into a 250 mL
polypropylene bottle previously weighted.
6. Add the supernatant into the 250 mL polypropylene bottle.
7. Add 30 mL of ammonia buffer solution on the bottom.
8. Shake the sample using a rotary shaker for 30 minutes.
9. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
10. Pour the supernatant into the 250 mL polypropylene bottle.
11. Using disposable Pasteur pipette, make-up to 200 g with acidified water with formic acid 0.5 %. This is the Extract A (for information, the pH is around 6.5).
Note: weight of extract A is used for residue calculation, as variable Weight EXt,a t A
12. Weigh 3.0 g of AG 50W-X8 resin previously washed into a conical centrifuge tube.
13. Using a disposable glass pipette, transfer an aliquot of 5 mL of Extract A
into the centrifuge tube.
14. Shake the sample using a rotary shaker for 10 minutes.
15. Centrifuge the sample (6000 rpm - ambient) for approx. 5 minutes : the supernatant obtained corresponds to Extract B (for information, the pH is around 2.5).
Note: this step of resin treatment is necessary to obtain a narrow H3P03 peak shape.
16. Dilute using a dilutor (or in a different way) ten times the extract B
using acidified water with formic acid 0.5 %. This is the Final Extract (for information, the pH is around 2.5).
17. Proceed to LC/MS/MS measurement, Chapter 3.3.
18. If necessary to dilute the Final Extract due to a concentration outside the calibration curve : use acidified water with formic acid 0.5 2.3 Analysis and Instrument Conditions The final extracts are injected into a high performance liquid chromatograph and detected by tandem mass spectrometry with electrospray ionisation.
The quantification is carried out by external standardisation using standards prepared in solvent.
Exemplary LC/MS/MS conditions that were used in the course of this method validation are listed in chapters 3.3.1 and 3.3.2. These conditions are given as a guidance and may have to be adapted for other HPLC-MS/MS systems.
2.3.1 HPLC Conditions Instrument: Binary pump Agilent 1100 Autosampler: CTC Analytics HTS PAL
Column: Hypercarb, 100 x 2.0 mm, 5 Nm Precolumn: none Injection Volume: 50 pL
Column temperature: ambient (about 25 C) Mobile Phase: Isocratic mode: 55 / 45 (v/v) Methanol + 2% formic acid / water + 2% formic acid Flow (Column): 200 pL/min Retention Times: about 3.1 min for phosphorous acid and 4.2 min for fosetyl-Al.
Remarks :
5 = It is necessary to wait about 2 hours the stabilisation of the HPLC system before injecting.
During a samples set, a light drift of retention time of both compounds can be observed.
= Hypercarb precolumn must not be used.
= Depending of the phase batch of Hypercarb column, the percentage of formic acid in the mobile phase could be adapted to improve peaks shape (from 0.5% to 2%).
10 = At the contrary, do not increase the HCOOH rate in the injection solvent.
The use of water at 0.5% formic acid as injection solvent is necessary to keep a narrow H3P03 peak shape.
2.3.2 MS/MS Conditions The experiments were performed on a triple-quadrupole mass spectrometer system, fitted with 15 an electrospray interface operated in the negative ion mode under MRM
(multiple reaction monitoring) conditions.
For instance:
Detector: Triple Quadrupole HPLC-MS/MS Mass Spectrometer, e.g. Sciex Instruments, API 4000 System 20 Source: TIS (Turbo Ion Spray) Temperature: 650 C
Scan Type: MRM-Mode (Multiple Reaction Monitoring Mode) Polarity: Negative ion mode Gas Flows: Nebulization Gas Air (GS1): 40 25 Turbo Gas Air (GS2): 60 Curtain Gas N2 (CUR): 15 Collision Gas N2 (CAD): 6 Collision Energy:
Compound Precursor Ion Product Ion Dwell Time Collision Energy Q1 Mass (amu) Q3 Mass (amu) (msec) (V) Fosetyl-Al 109 81 200 -16 Phosphorous acid 81 79 400 -22 30 Table 31: Mass spectrometer scan parameters for the quantifier ions used.
The detailed instrument settings used are given in chapters 3.3.1 and 3.3.2. Varying instrument systems or instrument parameters may result in different ion transitions and different relative intensities.
Note: Some mass spectrometer conditions are instrument specific. The spectrometer conditions should be optimised by a competent operator prior to analysis.
Details on MS/MS and LC conditions are given in Appendix 8.
The fragmentation pathways for the quantifier ions for fosetyl-Al and phosphorous acid are shown in Figure 1 and in Figure 2.
Figure 1: Proposed fragmentation pathway for fosetyl-Al OI - loss of C2H4 0 I _ HsC-H-O-p-O HO-P-O
m/z 109 m/z 81 Figure 2: Proposed fragmentation pathway for phosphorous acid II _ Ioss of H2 -H
m/z 81 m/z 79 2.3.3 Confirmatory transitions To confirm or exclude some interference or pollution in samples, the following transitions can be used in the same conditions described above :
Compound Precursor Ion Product Ion Dwell Time Collision Energy (V) Q1 Mass (amu) Q3 Mass (amu) (msec) fosetyl-Al 109 63 300 -38 phosphorous acid 81 63 400 -38 The fragmentation pathways for the confirmatory transitions for fosetyl-Al and phosphorous acid are shown iri Figure 3 and in Figure 4.
Figure 3: Proposed fragmentation pathway for fosetyl-Al II loss of C2H4 -2 H and H20 m/z 109 m/z 63 Figure 4: Proposed fragmentation pathway for phosphorous acid ~ - loss of H20 -H
m/z 81 m/z 63 Note : all recovery samples were also analysed using confirmatory transitions.
The results are given in Appendix 9.
2.4 Linearity of the Detector The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L.
Table 32: Standard concentrations prepared for the determination of detector linearity. The concentration corresponding to the LOQ is is printed in bold figures.
HPLC-MS/MS Standard Concentrations [pg/L]
fosetyl-Al 0.25 0.4 0.5 1 2.5 5 10 25 phosphorous acid 0.25 0.4 0.5 1 2.5 5 10 25 2.5 Storage Stability of Extracts The stability of sample extracts containing fosetyl-Al and phosphorous acid was not determined in this study.
2.6 Calculation 2.6.1 Calculation of Residues Evaluation in this case is performed according to the external standardisation using standards prepared in solvent.
During the analysis of each set of samples, the 8 standard solutions mentioned in Table 4 are injected once. Standards should be interspersed with samples to compensate for any minor change in instrument response.
For each compound, the peak area is plotted versus the concentration in order to establish a calibration curve obtained by linear regression weighting 1/x with least squares method.
The corresponding model to determine the concentration in final extracts is calculated using the Analyst Software (Version 1.4).
Each final extract is injected once using the same conditions as previously described for the standard solutions.
Using the predicting mathematical model previously established, the final concentration in tag/L
of each compound is determined for each injection.
For each compound, the amount of residue R, expressed in mg/kg is calculated, using the following formula :
R_ C x WeightExtractA x Density 1 x D
1000 x Weightsaõp,e where:
R : Determined amount of residue of fosetyl-Al or phosphorous acid in soil sample in mg/kg C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in pg/L
Weight EXtra. tA : Weight of the extract A in g, here 200 g Density-1 : 1 mL/g D : Dilution factor to obtain the Final Extract, here 10 Weight Sample : Sample weight of analytical sample in g, here 20 g Remarks :
= The density of all solutions used during the sample preparation (ammonia buffer solution and H20 at 0.5% HCOOH) is considered equal to 1 independently to room temperature. This allows to convert the extract weight into extract volume.
= If it is necessary to express phosphorous acid in fosetyl-Al equivalent, the ratio of the molecular weight must be used 354.1g/mol Ratio = =1.44 (82.0 x 3) g/mol because 1 mole fosetyl-Al (354.1g) gives 3 moles of phosphorous acid.
2.6.2 Calculation of Recovery Rates The concentration of each compound in pg/L is determined for the recovery sample according to 2.6.1.
The percent recovery rate is then calculated as follows :
Cx100 Rec =
A
where: Rec : Recovered amount found in fortified sample in %
C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in Ng/L
A : Fortified amount of fosetyl-Al or phosphorous acid in pg/L
2.6.3 Calculation of Relative Standard Deviation (RSD) The RSD is calculated as follows :
RSD (%) = S.D. / Mean Recovery x 100 %
E (R; - Rm)2 R; : recovery S. D. = [ wz Rm : mean recovery n-1 n : number of recoveries 3 Results and Discussion 3.1 Specificity and Selectivity The method allows the determination of fosetyl-Al and its metabolite (phosphorous acid) in soil samples.
The specificity of the method resulted from the HPLC separation in combination with the very selective MS/MS detection.
3.2 Apparent residues in Control Samples The method was validated using the two German soils Hofchen and Laacher Hof.
Two different soils were used in order to assess a possible influence of different soil characteristics. The soil samples were classified according to DIN and/or USDA
specifications.
Soil characteristics of the used soils are summarised in Table 33.
Complete soil characterisation is reported in the Appendix 10.
Table 33: Soil Types Soil Texture of Soil Organic Matter [%]
Hofchen silt loam (USDA) 1.58 Laacher Hof sandy loam (USDA) 2.06 A residue level estimation in control samples was performed. The results are listed in Table 34.
The apparent residues for all control samples were below 20% of the LOQ for each compound, i.e. < 0.01 mg/kg.
10 Table 34: Apparent residues in untreated control samples for fosetyl-Al and phosphorous acid Sample Material LOQ Apparent residues [mg/kg] [mg/kg]
fosetyl-AI phospho- fosetyl-Al phospho-rous acid rous acid Hofchen 0.05 0.05 < 10% LOQ < 20 /o LOQ
Laacher Hof 0.05 0.05 < 10% LOQ < 10% LOQ
3.3 Linearity of the Detectors and Matrix Effects The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using 15 standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L.
Experimental details can be found in Chapter 2.4.
In each chromatogram, the measured peak area of fosetyl-Al or phosphorous acid is plotted 20 versus the corresponding concentration of respectively fosetyl-Al or phosphorous acid contained in each standard solution, in order to obtain calibration curve of the form :
y = ax+b (1/x weighting) where : y = peak area, x = concentration in injected standard solution The results of the determination of detector response for LC/MS/MS are summarised inTable 35.
Table 35: Summary of the determination of detector linearity for LC/MS/MS.
phosphorous Detection Parameter fosetyl-Al acid LC/MS/MS Linear range [pg/L] 0.25 - 25 0.25 - 25 _...
...............................................................
...............................................................................
.................... ..................................
.................................................. ....................
............ _........ ................ _......... _......
No. of concentrations 7 or 8 7 or 8 ........................ ................ ................. _..... .......
............. _..._.._..._....................................
_............................. ........... ..................................
.... ....................... _.................... .................
_..................................................................
No. of injections 1 1 ...................................................... .......
_.............................. .............._.. .................
_............... _............. ..................... .......
................. .......................... ....................
_............... ............. _...............
.................................... _..................
1/x weighted 1/x weighted Model linear regression linear regression Correlation coefficient (R) 0.9999 - 0.9996 for standards prepared in solvent .......................................... _.......... _........... ._....
__.._................................
.................................................
.................................. _...... .............. e.
........................ .__................
_............................................................
Correlation coefficient (R) >_ 0.9997 0.9999 for matrix matched standards An excellent linear correlation between the injected amount of the analytes and the detector responses of LC/MS/MS was observed for standards in the range of 0.25 to 25 pg/L for both compounds, using either standards prepared in solvent or matrix matched standards.
The occurrence of matrix effects was monitored.
The results are shown in Table 36 and Table 37.
Table 36: Matrix effect evaluation for fosetyl-Al FL : Fortification Level Measurement using Number FL Standards in pure Matrix matched Sample Material of Values [mg/kg] ( ) solvent standards n Mean [%] RSD [%] Mean [%] RSD [%]
0.05 5 72 2.7 81 3.8 0.05 5 72 2.7 81 3.8 Hofchen 0.5 5 78 1.1 78 3.2 0.05 5 71 2.3 67 5.7 Laacher Hof 0.5 5 80 1.4 76 5.8 Table 37: Matrix effect evaluation for Phosphorous acid FL: Fortification Level Measurement using Number FL Standards in pure Matrix matched Sample Material of Values [mg/kg] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
0.05 5 91 3.2 76 10.0 Hofchen 0.5 5 85 2.3 77 3.9 0.05 5 84 9.0 72 14.4 Laacher Hof 0.5--t 5 84 2.0 78 3.1 The results presented in the two previous Tables 36 and 37 show that :
- no significant difference is observed when the measurement of fosetyl-Al is established using either standards prepared in solvents, or matrix matched standards.
- the measurement of phosphorous acid is better (higher mean recoveries and lower RSD found) when it is established using standards prepared in solvents, instead of using matrix matched standards.
For all these reasons, we advice to use standards prepared in solvents.
3.4 Limit of Quantification and Recovery Experiments The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of ~ 20% could be obtained.
The LOQ
was set at 0.050 mg/kg for each compounds in soils samples.
To validate the method for these matrices, control samples were fortified with a defined amount of fosetyl-Al and phosphorous acid prior to analysis.
3.5 Recovery Rates The detailed recovery results obtained are listed in Tables 38 and 39.
All results given in Tables 38 and 39 have been obtained by using standards prepared in solvents and the quantifier ion (see 3.3.2).The results obtained with the confirmatory transition are given in Appendix 9.
Table 38: Recovery rates obtained for fosetyl-Al, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [%] [%]
0.05 Hofchen 75 71 70 72 73 72 2.7 0.05 Laacher Hof 70 72 71 74 70 71 2.3 mean of all 0.05 mg/kg single values 72 2.4 0.5 Hofchen 79 79 79 77 78 78 1.1 0.5 Laacher Hof 80 80 79 78 81 80 1.4 mean of all 0.5 mg/kg single values 79 1.5 mean of all Hofchen samples 75 4.7 mean of all Laacher Hof samples 76 6.0 overall mean 75 5.3 Table 39:Recovery rates obtained for Phosphorous acid, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [%] [%]
0.05 Hofchen 95 90 87 91 91 91 3.2 0.05 Laacher Hof 98 80 82 81 81 84 9.0 mean of all 0.05 mg/kg single values 88 7.3 0.5 Hofchen 87 84 86 82 84 85 2.3 0.5 Laacher Hof 84 83 84 83 87 84 2.0 mean of all 0.5 mg/kg single values 84 2.0 mean of all Hofchen samples 88 4.6 mean of all Laacher Hof samples 84 6.2 overall mean 86 5.6 The obtained recovery rates are summarised below in Table 40.
In total 20 recovery rates were determined for each compound.
Table 40: Summary of the recovery data for the determination of accuracy and repeatability;
RSD: relative standard deviation Phosphorous Number Parameter Fosetyl-Al acid of values n Single recoveries [%] 70 - 81 80 - 98 20 Mean recoveries per fortification level [%] 72 - 79 84 - 88 10 Accuracy Mean recoveries per kind of soils [%] 75 - 76 84 - 88 10 Overall mean [%] 75 86 20 RSD per fortification level [%] 1.5 - 2.4 2.0 - 7.3 10 Repeatability RSD per kind of soils [%] 4.7 - 6.0 4.6 - 6.2 10 Overall RSD [%] 5.3 5.6 20 The previous table shows that :
The single recovery rates were in the range of 70 to 81 % for fosetyl-Al and of 80 to 98 % for phosphorous acid. All mean recoveries rates were in the range of 70 to 110 %.
All RSD were well below 20 %.
4 Evaluation and Discussion The presented residue analytical method modification 00974/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in soils by LC/MS/MS.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are extracted from the soil samples by shaking with ammonia buffer solution. This extract is then treated with a cationic resin and a final dilution is done before the analysis by LCMSMS. The residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation using standards prepared in pure solvent.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L. The detector response was linear in these ranges.
The occurrence of matrix effects was monitored - no significant difference is observed when the measurement of fosetyl-Al is established using either standards prepared in solvents, or matrix matched standards ;
- the measurement of phosphorous acid is better (higher mean recoveries and lower RSD found) when it is established using standards prepared in solvents, instead of using matrix matched standards.
For all these reasons, we advice to use standards prepared in solvents.
The apparent residues for all control samples were below 20% of the LOQ for each compound, i.e. < 0.01 mg/kg.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of D 20% could be obtained.
The LOQ
was set at 0.050 mg/kg for each compounds in soils samples.
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 70 to 81 % for fosetyl-Al and of 80 to 98 % for phosphorous acid. All mean recoveries rates were in the range of 70 to 110 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
All RSD were well below 20 %. Thus the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so this method modification has been validated successfully.
Note : during analysis, for each sample set, it is necessary to do a blank reagent without soil sample to be sure that no phosphorous acid contamination (< 30% LOQ) coming from sample preparation is found.
Remarks :
= standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
= Before start of validation / measurements equipment / chemicals should be tested for any residues of phosphorous acid.
= If some contamination is observed, see if the use of special HPLC vials (e.g.
polypropylene vials, Agilent, art. 5182-0567) can be helpful to reduce the background for phosphorous acid.
Appendix 7 Flow Diagram of Residue Method 00974/M001 Soil sample preparation procedure Main point :for each set of sanzples, it is necessary to do a blank reagent witliout soil sample to be sure that no H3P03 contamination (< 30% LOQJ
coniing from sample preparation is found (that is why disposable consumables are used) 20.0 g of soil sample into 125 mL polypropylene bottle (Add here 100,uL of the fortifying solution for LOQ recoveries or 100,uL of the fortifying solution for IOLOQ recoveries) +
30 mL of ammonia buffer solution Mechanical agitation (30 minutes) at ambient temperature Centrifugation (5 minutes at 3600rpm at -5 C) Bottom + 30 ml of ammonia buffer solution Put the floating into a weighted I disposable 250 mL polypropylene Mecltanical agitation ( 30 bottle where about 100 g of acidified minutes) at ambient temperature water at 0.5%formic acid were ~ already poured Centrifugation (5 minutes at 3600rpin at -5 C) Floating Make-up to 200 g with H20 at 0. 5% HCOOH, using Pasteur pipette : Extract A
Weigla 3 g of waslied AG 50W-X8 resin into a conical centrifuge tube Transfer about 5 mL of Extract A into this centrifuge tube, using disposable pipette Mecizanichal agitation for J minutes at anibient temperature Then centrifuge (5 minutes at - 6000 rpm - ambient):
the supernatant obtained corresponds to Extract B
Dilute 10 times the extract B in H20 + 0.5% xcooH = Final Extract for LCMSMS
If necessary to dilute the Final Extract due to concentration outside the calibration curve : use H20 + 0.5% HCOOH
Remark : - means 'around '. Study : 05-17 Appendix 8 Details on LC-MS/MS conditions Comment:
Synchronization Mode: LC Sync Auto-Equilibration: Off Acquisition Duration: 10min1sec Number Of Scans: 455 Periods In File: 1 Acquisition Module: Acquisition Method Software version Analyst 1.4 MS Method Properties:
Period 1:
--------------Scans in Period: 455 Relative Start Time: 0.00 msec Experiments in Period: 1 Period 1 Experiment 1:
----------------------------Scan Type: MRM (MRM) Polarity: Negative Scan Mode: N/A
Ion Source: Turbo Spray Resolution Q1: Unit Resolution Q3: Unit Intensity Thres.:0.00 cps Settling Time: 0.0000 msec MR Pause: 5.0070 msec MCA: No Step Size: 0.00 amu Quantifier transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 78.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -22.00 -22.00 CXP -5.00 -5.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 80.90 200.00 DP -45.00 -45.00 (fosetyl-Al) CE -16.00 -16.00 CXP -1.00 -1.00 Confirmatory transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 62.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -38.00 -38.00 CXP -1.00 -1.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 62.90 300.00 DP -45.00 -45.00 (fosetyl-AI) CE -38.00 -38.00 CXP -5.00 -5.00 Parameter Table (Period I Experiment 1):
CAD: 6.00 CUR: 15.00 GS1: 40.00 GS2: 60.00 TEM: 650.00 ihe: ON
IS: -4500.00 EP -10.00 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Binary Pump Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Dead Volume (pl): 40.0 Maximum Flow Ramp (ml/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 Step Table:
Step Total Time(min) Flow Rate(pl/min) A(%) B(%) 0 0.00 200 55.0 45.0 1 10.00 200 55.0 45.0 Left Compressibility: 50.0 Right Compressibility: 115.0 Left Dead Volume (pl): 40.0 Right Dead Volume (NI):40.0 Left Stroke Volume (pl): -1.0 Right Stroke Volume (pI): -1.0 Left Solvent: Al (methanol + 2% formic acid) Right Solvent: B2 (water + 2% formic acid) CTC PAL Autosampler Method Properties :
Loop Volumel (pl): 50 Loop Volume2 (pl): 100 Injection Volume (NI): 100.000 Method Description:
Syringe: 250u1 Analyst LC-Inj Air Volume (pl) 0 Pre Clean with Solvent 1() 2 Pre Clean with Solvent 2() 1 Pre Clean with Sample () 0 Filling Speed (pl/s) 50 Filling Strokes () 0 Inject to LC Vlvl Injection Speed (pl/s) 50 Pre Inject Delay (ms) 500 Post Inject Delay (ms) 500 Post Clean with Solvent 1() 3 Post Clean with Solvent 2() 2 Valve Clean with Solvent 1() 2 Valve Clean with Solvent 2O 1 Gas pressure Autosampler CTC Analytics HTS Pal (GLP n 1303) N2 4 bar Peltier rack 10 C
Air GSI/GS2 gas 7 bar Wash solvent 1: H20 + 0.5%HCOOH
Air Exhaust gas 4 bar Wash solvent 2: MeOH
Pumps Analytical LC pump.:
Binary 1 pump Agilent 1100 (GLP n 1296):
Al = Methanol + 2% Formic Acid Valco valve used Column selector used B2 = H20 + 2% Formic Acid GLP n 1289 GLP n 1356 Source GLP n 1291 Probe TurbolonSpray Pump for making-up solvent : GLP n 1288 Horizontal Position 7 (x axis) Vertical Position 7 axis) Ca illar exit 1 mm Mass Spectrometer API 4000 Device GLP n 1292 Binary 2 pump Agilent 1100 (GLP n 1297):
A2 = H20 + 2% Formic Acid Column : at room temperature B2 = Acetonitrile Precolumn : none Column : SMAR 68-1 Thermo Hypercarb 100 x 2.0mm 5 m Appendix 9 Results obtained with confirmatory transitions All results in Tables 41 and 42 have been obtained by using standards prepared in solvents.
Table 41: Recovery rates obtained for Fosetyl-Al, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [%] [%]
0.05 Hofchen 77 73 72 76 74 74 2.8 0.05 Laacher Hof 72 72 76 76 74 74 2.7 mean of all 0.05 mg/kg single values 74 2.6 0.5 Hofchen 79 79 80 76 78 78 1.9 0.5 Laacher Hof 80 80 79 79 81 80 1.0 mean of all 0.5 mg/kg single values 79 1.7 mean of all Hofchen samples 76 3.6 mean of all Laacher Hof samples 77 4.4 overall mean 77 3.9 Table 42: Recovery rates obtained for Phosphorous acid, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [ /a] [%]
0.05 Hofchen 92 87 85 87 85 87 3.3 0.05 Laacher Hof 87 75 78 73 79 78 6.8 mean of all 0.05 mg/kg single values 83 7.4 0.5 Hofchen 86 85 85 81 84 84 2.3 0.5 Laacher Hof 83 83 83 82 86 83 1.8 mean of all 0.5 mg/kg single values 84 2.0 mean of all Hofchen samples 86 3.3 mean of all Laacher Hof samples 81 5.6 overall mean 83 5.3 All results obtained above with confirmatory transition comply with European requirements.
Appendix 10 Soil characterisation Soil Hofchen Soil Hofchen, plot 4011: 0- 30 cm soil layer pH (in CaC12 solution) 6.7 pH (in H20) 7.4 Organic Carbon [%] 0.92 Organic Matter [%] * 1.58 Cation Exchange Capacity 12.4 [meq / 100 g dry soil]
max. Water Holding Capacity 39.4 [g / 100 g dry soil]
Textural Description according to USDA
Fraction [%]
Clay 19.4 (<0.002 mm) Silt 76.3 (0.002-0.050 mm) Sand 4.3 (0.050-2.000 mm) Soil type: silt loam * Organic matter = Organic carbon x 1.72 Soil Laacher Hof Soil Laacher Hof, plot 712/718: 0- 30 cm soil layer pH (in CaCI2 solution) 6.8 pH (in H20) 7.4 Organic Carbon [%] 1.20 Organic Matter [%] 2.06 Cation Exchange Capacity 9.8 [meq / 100 g dry soil]
max. Water Holding Capacity 37.9 [g/100gdry soil]
Textural Description according to USDA
Fraction [%]
Clay 12.0 (<0.002 mm) Silt 18.3 (0.002-0.050 mm) Sand 69.7 (0.050-2.000 mm) Soil type: sandy loam * Organic matter = Organic carbon x 1.72
.......... .....................
...................................................
_............................ _._............... . .. . .......
.................................. ................... .......................
_.
fosetyl-Al 0.001 45 59 71 59 15.7 standards in Overall Mean and RSD 45 37.1 pure solvent 0.0001 51 63 64 60 9.2 ............................................................. ..... _.........
--.......... __..... ................ .................... .................
_......................................... ........ _....... .....
................. ...... ..... _.......... ....... _.............
phosphorous 0.001 69 73 71 70 3.5 acid Overall Mean and RSD 65 9.8 0.0001 103 102 111 112 10.1 ................. .......... ........................... _...............
........................
............................................................ ...........
.................... ----............ .... .......................... _......
_.... ._...........................................
fosetyl-Al 0.001 98 127 151 126 14.9 matrix matched Overall Mean and RSD 119 13.8 standards 0.0001 89 106 109 103 8.2 _........
............. .......... _............ _........ .......................
._............................ ....................
.......................................... __..........................
........ ...................... _........ _._.... .... ....................
_......
phosphorous 0.001 105 110 108 105 3.6 acid Overall Mean and RSD 104 6.0 Appendix 8 Flow chart of variant method Main point : for each set of samples, it is necessary to do a blank reagent where water sample is replaced by H20 milliQ to be sure that no H3P03 contamination (< 30% LOQ) coming from sample preparation is found.
0.6 g of washed AG 50W-X6 resin (in disposable Nalgene bottle PP) +
20.0 g of water sample (using disposable Pasteur Pipette) (Add here using a dilutor 200 NL of the fortifying solution for LOQ recoveries or 200 NL of the fortifying solution for IOLOQ recoveries) Mechanical agitation (10 minutes) at ambient temperature :
Extract A corresponds to Fil7al Extract HPLC Measurement with Electrospray MS/MS detection If necessary to dilute the Final Extract due to concentration outside the calibration curve : use final extract of control sample s (because matrix matched standards are used for calibration) Appendix 9 Results obtained with variant method Drinking water Fortification Recoveries Calibration Compound Level Single curve Values [%] Mean [%] RSD [%]
[mg/L]
0.0001 99 97 99 97 2.1 ..................................... _........._..__.... . ....... .........
....
_............_.................................................................
............................................
............................................. ..._........... _............
_.__....._..
fosetyl-Al 0.001 101 98 91 96 3.9 standards in pure solvent Overall Mean and RSD 97 3.0 0.0001 no result ............................................... ........ __.......... .......
............. ........ ...............................................
_.._..... .. . ...............................
............................................................................
...... _.......
phosphorous 0.001 105 100 101 101 2.0 acid 101 100 Overall Mean and RSD 101 2.0 0.0001 106 104 106 104 2.0 .............................................................. _...........
.................... ................ ..................................
......... _..__............................ _... ...............
..........._....._................... ............
_................................
fosetyl-Al 0.001 101 98 92 96 3.5 matrix 95 96 matched standards Overall Mean and RSD 100 5.0 0.0001 no result .e ....................................................................
....... ....._..........
_.._..............................................................
.................... _......... ......... _... ......... .....
........_.................... ..... _.... ...... ............................
phosphorous 0.001 98 92 93 94 2.7 acid 93 92 Overall Mean and RSD 94 2.7 Surface water Fortification Recoveries Calibration Compound Level Sin le Values % Mean % RSD [%]
g [ ] [ ] ]
[mg/L]
0.0001 103 87 101 97 7.9 ...
........................................ .... ............................
....... _.......................... _........... _..................... _.....
...... ....... _.. - .._.........---.............. _.............. _.....
_....... _.......... .._........................................
fosetyl-Al 0.001 101 102 98 101 1.7 standards in pure solvent Overall Mean and RSD 99 5.7 0.0001 no result _............. ...... ........... _.......................................
.................... ..................... _..............
_.......................... ..................................................
....... _..................................
_..................................... ..........
phosphorous 0.001 97 97 94 97 2.1 acid 99 99 Overall Mean and RSD 97 2.1 0.0001 104 88 102 98 7.9 .............. ....... .......... ....................... _.................
....... _........... ....................... .... ._...... . _....
........................................................................
.............. ......... _...................
................................... _..........
fosetyl-Al 0.001 101 101 98 100 1.6 matrix 102 99 matched standards Overall Mean and RSD 99 5.4 0.0001 no result ............ ................... _......................................... _ ..................................................................
....................................... __.... _...................
........................................... ..........................
_.................... ....
phosphorous 0.001 93 93 90 93 2.2 acid 95 95 Overall Mean and RSD 93 2.2 Example 5 :
This detailed example concerns the analysis of fosetyl-Al and of phosphorous acid using soil samples. This example is a modification M001 to the Analytical Method 00974 for the determination of residues of fosetyl-Al and its metabolite (Phosphorous acid) in soils.
Data Requirement = EU Council Directive 91/414/EEC amended by Commission Directive 96/46/EC
= European Commission Guidance Document for Generating and Reporting Methods of Analysis in Support of Pre-Registration Data Requirements for Annex II (Part A, Section 4) and Annex III (Part A, Section 5) of Directive 91/414, SANCO/3029/99 = European Commission Guidance Document for Residue Analytical Methods, SANCO/825/00 rev.7 Summary The presented residue analytical method modification 00974/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in soils by LC/MS/MS.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are extracted from the soil samples by shaking with ammonia buffer solution. This extract is then treated with a cationic resin and a final dilution is done before the analysis by LCMSMS. The residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation using standards prepared in pure solvent.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L.
The occurrence of matrix effects was monitored.
The conclusion is that :
- no significant difference is observed when the measurement of fosetyl-Al is established using either standards prepared in solvents, or matrix matched standards ;
- the measurement of phosphorous acid is better (higher mean recoveries and lower RSD found) when it is established using standards prepared in solvents, instead of using matrix matched standards.
For all these reasons, standards prepared in solvents should be used.
The apparent residues for all control samples were below 20 / of the LOQ for each compound, i.e. < 0.01 mg/kg.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of 20% could be obtained.
The LOQ was set at 0.050 mg/kg for each compounds in soils samples.
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 70 to 81 % for fosetyl-Al and of 80 to 98 % for phosphorous acid. All mean recoveries rates were in the range of 70 to 110 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
All RSD were well below 20 %. Thus the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so this method modification has been validated successfully.
1 Introduction Fosetyl-Al is a fungicide.
The method modification 00974/M001 presented in this report was validated in order to suppress the steps of derivatization, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00974 from 0.100 mg/kg to 0.050 mg/kg for fosetyl-Al and phosphorous acid.
Table 29: LOQ and principle of analytical determination Compound Fosetyl-Al Phosphorous acid Determined as Fosetyl-Al Phosphorous acid Calculated as Fosetyl-Al Phosphorous acid Principle of Determination LC/MS/MS LC/MS/MS
LOQi [mg/kg] Soil sample 0.05 0.05 i: e ine as e owes va i a e o i ica ion eve 1.1 Citation of the Original Method Original Method : 00974 Compounds : fosetyl-Al and its metabolite (phosphorous acid) Reason for Modification : =Suppress the steps of derivatization.
i, defined as the lowest validated fortification level =Change analysis and detection modes from GC/FPD
to LC/MS/MS.
=Decrease the LOQ from 0.100 mg/kg to 0.050 mg/kg for fosetyl-Al and phosphorous acid 1.2 Physical and Chemical Properties See example 3.
2 Experimental Section 10 2.1 Materials 2.1.1 Apparatus Standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
15 = Balances :
- accuracy 0.1 mg (analytical standards) (e.g. Mettler AT261 range) - accuracy 0.1 g (samples) (e.g. Mettler PM2000) = Dilutor (e.g. Hamilton MicroLab 1000 plus) = Rotary shaker (e.g. Heidolph REAX 2) 20 = Centrifuge (e.g. Hermle Z513fC) (ex Hettich EBA12) = HPLC (e.g. Binary Pump Agilent 1100) = Autosampler (e.g. CTC Analytics HTC PAL) = Triple Quadrupole HPLC-MS/MS Mass Spectrometer 25 (e.g. Sciex Instruments, API 4000 System) = Column (e.g. Hypercarb, 100 x 2.0 mm, 5pm ) 3.1.2 Reagents and Supplies = Acetone (e.g. Pestipur SDS) 30 = Methanol (e.g. Pestipur SDS) = Formic acid (e.g. Analytical reagent Merck) = Ammonium hydrogen carbonate (e.g. Normapur Merck) = ammonia solution 32% (e.g. Rectapur Merck) = Cationic resin (AG 50W-X8, 20-50 Meshs, hydrogen form) (e.g. Bio Rad) 35 = GF/A filters (125 mm), (e.g. Whatman) = Polypro bottles (1000 mL, wide opening) (e.g. Nalgen) = Polypro bottles (250 mL, wide opening) (e.g. Nalgen) = Polypro bottles (125 mL, wide opening) (e.g. Nalgen) = Polypro bottles (60 mL, wide opening) (e.g. Nalgen) 40 = Polypro funnels (67mm) (e.g. Marylands Plastics) = Conical centrifuge tube (15 mL) (e.g. Merck) = Solvent for dilution : Water with 0.5 % HCOOH
= Mobile phase solvent : Water with 2 % HCOOH
Methanol with 2 % HCOOH
= ammonia buffer solution : pour 500 mL of water in a 1000 mL volumetric flask, add 20 g of ammonium hydrogen carbonate and mix with a magnetic stirrer until complete solubilisation. Add 15 mL of ammonia solution 32% and complete to 1000 mL with water.
2.1.3 Reference Item Only sufficiently characterised and certified item was used as reference item.
The reference item was made available by Bayer CropScience GmbH produkt Analytik, G864, Industriepark Hochst, D-65926 Frankfurt-am-Main, Germany.
Table 30: Reference item data Name of Substance Batch Number Content [%] Date of Expiry fosetyl-Al 12/1080 97.6 February 20, 2006 phosphorous acid 04911 DN 96.2 March 02, 2008 2.1.4 Standard Solutions Stock and standard solutions were stored protected from light in a refrigerator at around 5 C.
Stock solutions (1000 mg/L) Into a 100 mL amber screw-cap flask, weigh accurately between 20 and 50 mg of reference item. Using a burette, add a volume of water to obtain a stock solution of exactly 1000 mg/L. Mix thoroughly until complete dissolution using a magnetic stirrer. Two separate stock solutions must be prepared for each compound. After comparison of these two stock solutions, they are mixed.
Mixture solutions Pipette 5 mL of each stock solution using a class "A+" pipette. Pour into a class "A" 50 mL
volumetric flask. Adjust volume with water, cap and mix by shaking (100 mg/L
of each compound). Two different mixture solutions are prepared.
Fortifying standard solutions By dilution in water of one of the mixture solution, which is also used as fortifying solution for recoveries at 10LOQ level (100 mg/L of each compound), prepare the fortifying standard solution used for recoveries at LOQ level (10 mg/L of each compound).
Intermediate standard solution By serial dilutions of the other mixture solution, prepare the intermediate standard solution at 1.0 mg/L of each compound using water.
Before use, the intermediate solution and the fortifying standard solution used for recoveries at LOQ level are compared to validate their preparation.
Standard solutions in solvent used for calibration To obtain the standard solutions used for calibration, dilute extemporaneously using a dilutor (or in a different way) and water with 0.5% formic acid, the intermediate standard solution to obtain the following concentrations: 0.25, 0.4, 0.5, 1, 2.5, 5, 10 and 25 pg/L.
Matrix matched standard solutions The occurrence of matrix effects was monitored and the measurement of both compounds is established using matrix matched standards in both sample materials.
From the intermediate standard solution, the dilutions are the same as preparation of standard solutions in solvent, except the dilution mixture which is the final extract of a control sample.
Remarks :
= 20 to 25 mL of final extract are necessary to make all dilutions.
= to avoid the use of standard laboratory glass consumable, which could bring some H3P03 contamination, the dilution of the control sample extract B is done by weighing. Using disposable Pasteur pipette weigh 3.0 g of extract B into a 60 mL polypropylene bottle. Using another disposable Pasteur pipette, make-up to 30.0 g with acidified water with formic acid 0.5 % : this is the control sample final extract used as dilution mixture to prepare matrix matched standard solutions.
2.1.5 Stability of the standard solutions The stock solutions, stored protected from light in a refrigerator at around 5 C, were found to be stable for 9 months and a half.
2.2 Residue Analytical Methodology Some modifications compared to the original analytical method were introduced.
The method modification 00974/M001 presented in this report was validated in order to suppress the steps of derivatization, to change the analysis and detection modes and to decrease the Limit of Quantification (LOQ) of original method 00974 from 0.100 mg/kg to 0.050 mg/kg for each compound.
= The Limit of Quantification was decreased from 0.100 mg/kg to 0.050 mg/kg for fosetyl-Al and phosphorous acid.
= The derivatization step was suppressed.
= The quantification was carried out by LC/MS/MS instead of GC/FPD.
All modifications were included in the description below.
A flow chart of the method is given in Appendix 7.
Note : during analysis, for each sample set, it is necessary to do a blank reagent without soil sample to be sure that no phosphorous acid contamination (< 30 lo LOQ) coming from sample preparation is found.
Remark : standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
For recovery experiments, samples are fortified by adding the appropriate standard solution to the sample material after weighing and before shaking.
Preparation of the cationic resin :
1. Weigh about 25 g of AG 50W-X8 resin into a 1000 mL polypropylene bottle.
2. Add about 500 mL of water.
3. Shake using a rotary shaker for about 10 minutes.
4. Discard the supernatant water.
5. Do steps 2 to 4 a second time.
6. Do steps 2 to 4 a third time.
7. Filtrate residual water and resin through two GF/A filters put in a polypropylene funnel and previously rinsed with water.
Remark: resin is prepared either just before use or in advance, stored at ambient temperature and rehydrated just before use.
Caution: phosphorous acid interferences could be observed if the resin is not washed as described above.
Samples preparation :
1. Weigh 20.0 g of homogeneous sample material into a 125 mL polypropylene bottle.
Note: weight of the sample is used for residue calculation, as variable Weight Sample ' 2. Add 30 mL of ammonia buffer solution.
3. Shake the sample using a rotary shaker for 30 minutes at ambient temperature.
4. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
5. Pour about 100 g of acidified water with formic acid 0.5 % into a 250 mL
polypropylene bottle previously weighted.
6. Add the supernatant into the 250 mL polypropylene bottle.
7. Add 30 mL of ammonia buffer solution on the bottom.
8. Shake the sample using a rotary shaker for 30 minutes.
9. Centrifuge the extract (3600 rpm - 5 C) for approx. 5 minutes.
10. Pour the supernatant into the 250 mL polypropylene bottle.
11. Using disposable Pasteur pipette, make-up to 200 g with acidified water with formic acid 0.5 %. This is the Extract A (for information, the pH is around 6.5).
Note: weight of extract A is used for residue calculation, as variable Weight EXt,a t A
12. Weigh 3.0 g of AG 50W-X8 resin previously washed into a conical centrifuge tube.
13. Using a disposable glass pipette, transfer an aliquot of 5 mL of Extract A
into the centrifuge tube.
14. Shake the sample using a rotary shaker for 10 minutes.
15. Centrifuge the sample (6000 rpm - ambient) for approx. 5 minutes : the supernatant obtained corresponds to Extract B (for information, the pH is around 2.5).
Note: this step of resin treatment is necessary to obtain a narrow H3P03 peak shape.
16. Dilute using a dilutor (or in a different way) ten times the extract B
using acidified water with formic acid 0.5 %. This is the Final Extract (for information, the pH is around 2.5).
17. Proceed to LC/MS/MS measurement, Chapter 3.3.
18. If necessary to dilute the Final Extract due to a concentration outside the calibration curve : use acidified water with formic acid 0.5 2.3 Analysis and Instrument Conditions The final extracts are injected into a high performance liquid chromatograph and detected by tandem mass spectrometry with electrospray ionisation.
The quantification is carried out by external standardisation using standards prepared in solvent.
Exemplary LC/MS/MS conditions that were used in the course of this method validation are listed in chapters 3.3.1 and 3.3.2. These conditions are given as a guidance and may have to be adapted for other HPLC-MS/MS systems.
2.3.1 HPLC Conditions Instrument: Binary pump Agilent 1100 Autosampler: CTC Analytics HTS PAL
Column: Hypercarb, 100 x 2.0 mm, 5 Nm Precolumn: none Injection Volume: 50 pL
Column temperature: ambient (about 25 C) Mobile Phase: Isocratic mode: 55 / 45 (v/v) Methanol + 2% formic acid / water + 2% formic acid Flow (Column): 200 pL/min Retention Times: about 3.1 min for phosphorous acid and 4.2 min for fosetyl-Al.
Remarks :
5 = It is necessary to wait about 2 hours the stabilisation of the HPLC system before injecting.
During a samples set, a light drift of retention time of both compounds can be observed.
= Hypercarb precolumn must not be used.
= Depending of the phase batch of Hypercarb column, the percentage of formic acid in the mobile phase could be adapted to improve peaks shape (from 0.5% to 2%).
10 = At the contrary, do not increase the HCOOH rate in the injection solvent.
The use of water at 0.5% formic acid as injection solvent is necessary to keep a narrow H3P03 peak shape.
2.3.2 MS/MS Conditions The experiments were performed on a triple-quadrupole mass spectrometer system, fitted with 15 an electrospray interface operated in the negative ion mode under MRM
(multiple reaction monitoring) conditions.
For instance:
Detector: Triple Quadrupole HPLC-MS/MS Mass Spectrometer, e.g. Sciex Instruments, API 4000 System 20 Source: TIS (Turbo Ion Spray) Temperature: 650 C
Scan Type: MRM-Mode (Multiple Reaction Monitoring Mode) Polarity: Negative ion mode Gas Flows: Nebulization Gas Air (GS1): 40 25 Turbo Gas Air (GS2): 60 Curtain Gas N2 (CUR): 15 Collision Gas N2 (CAD): 6 Collision Energy:
Compound Precursor Ion Product Ion Dwell Time Collision Energy Q1 Mass (amu) Q3 Mass (amu) (msec) (V) Fosetyl-Al 109 81 200 -16 Phosphorous acid 81 79 400 -22 30 Table 31: Mass spectrometer scan parameters for the quantifier ions used.
The detailed instrument settings used are given in chapters 3.3.1 and 3.3.2. Varying instrument systems or instrument parameters may result in different ion transitions and different relative intensities.
Note: Some mass spectrometer conditions are instrument specific. The spectrometer conditions should be optimised by a competent operator prior to analysis.
Details on MS/MS and LC conditions are given in Appendix 8.
The fragmentation pathways for the quantifier ions for fosetyl-Al and phosphorous acid are shown in Figure 1 and in Figure 2.
Figure 1: Proposed fragmentation pathway for fosetyl-Al OI - loss of C2H4 0 I _ HsC-H-O-p-O HO-P-O
m/z 109 m/z 81 Figure 2: Proposed fragmentation pathway for phosphorous acid II _ Ioss of H2 -H
m/z 81 m/z 79 2.3.3 Confirmatory transitions To confirm or exclude some interference or pollution in samples, the following transitions can be used in the same conditions described above :
Compound Precursor Ion Product Ion Dwell Time Collision Energy (V) Q1 Mass (amu) Q3 Mass (amu) (msec) fosetyl-Al 109 63 300 -38 phosphorous acid 81 63 400 -38 The fragmentation pathways for the confirmatory transitions for fosetyl-Al and phosphorous acid are shown iri Figure 3 and in Figure 4.
Figure 3: Proposed fragmentation pathway for fosetyl-Al II loss of C2H4 -2 H and H20 m/z 109 m/z 63 Figure 4: Proposed fragmentation pathway for phosphorous acid ~ - loss of H20 -H
m/z 81 m/z 63 Note : all recovery samples were also analysed using confirmatory transitions.
The results are given in Appendix 9.
2.4 Linearity of the Detector The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L.
Table 32: Standard concentrations prepared for the determination of detector linearity. The concentration corresponding to the LOQ is is printed in bold figures.
HPLC-MS/MS Standard Concentrations [pg/L]
fosetyl-Al 0.25 0.4 0.5 1 2.5 5 10 25 phosphorous acid 0.25 0.4 0.5 1 2.5 5 10 25 2.5 Storage Stability of Extracts The stability of sample extracts containing fosetyl-Al and phosphorous acid was not determined in this study.
2.6 Calculation 2.6.1 Calculation of Residues Evaluation in this case is performed according to the external standardisation using standards prepared in solvent.
During the analysis of each set of samples, the 8 standard solutions mentioned in Table 4 are injected once. Standards should be interspersed with samples to compensate for any minor change in instrument response.
For each compound, the peak area is plotted versus the concentration in order to establish a calibration curve obtained by linear regression weighting 1/x with least squares method.
The corresponding model to determine the concentration in final extracts is calculated using the Analyst Software (Version 1.4).
Each final extract is injected once using the same conditions as previously described for the standard solutions.
Using the predicting mathematical model previously established, the final concentration in tag/L
of each compound is determined for each injection.
For each compound, the amount of residue R, expressed in mg/kg is calculated, using the following formula :
R_ C x WeightExtractA x Density 1 x D
1000 x Weightsaõp,e where:
R : Determined amount of residue of fosetyl-Al or phosphorous acid in soil sample in mg/kg C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in pg/L
Weight EXtra. tA : Weight of the extract A in g, here 200 g Density-1 : 1 mL/g D : Dilution factor to obtain the Final Extract, here 10 Weight Sample : Sample weight of analytical sample in g, here 20 g Remarks :
= The density of all solutions used during the sample preparation (ammonia buffer solution and H20 at 0.5% HCOOH) is considered equal to 1 independently to room temperature. This allows to convert the extract weight into extract volume.
= If it is necessary to express phosphorous acid in fosetyl-Al equivalent, the ratio of the molecular weight must be used 354.1g/mol Ratio = =1.44 (82.0 x 3) g/mol because 1 mole fosetyl-Al (354.1g) gives 3 moles of phosphorous acid.
2.6.2 Calculation of Recovery Rates The concentration of each compound in pg/L is determined for the recovery sample according to 2.6.1.
The percent recovery rate is then calculated as follows :
Cx100 Rec =
A
where: Rec : Recovered amount found in fortified sample in %
C : Concentration of fosetyl-Al or phosphorous acid found in the analysed extract in Ng/L
A : Fortified amount of fosetyl-Al or phosphorous acid in pg/L
2.6.3 Calculation of Relative Standard Deviation (RSD) The RSD is calculated as follows :
RSD (%) = S.D. / Mean Recovery x 100 %
E (R; - Rm)2 R; : recovery S. D. = [ wz Rm : mean recovery n-1 n : number of recoveries 3 Results and Discussion 3.1 Specificity and Selectivity The method allows the determination of fosetyl-Al and its metabolite (phosphorous acid) in soil samples.
The specificity of the method resulted from the HPLC separation in combination with the very selective MS/MS detection.
3.2 Apparent residues in Control Samples The method was validated using the two German soils Hofchen and Laacher Hof.
Two different soils were used in order to assess a possible influence of different soil characteristics. The soil samples were classified according to DIN and/or USDA
specifications.
Soil characteristics of the used soils are summarised in Table 33.
Complete soil characterisation is reported in the Appendix 10.
Table 33: Soil Types Soil Texture of Soil Organic Matter [%]
Hofchen silt loam (USDA) 1.58 Laacher Hof sandy loam (USDA) 2.06 A residue level estimation in control samples was performed. The results are listed in Table 34.
The apparent residues for all control samples were below 20% of the LOQ for each compound, i.e. < 0.01 mg/kg.
10 Table 34: Apparent residues in untreated control samples for fosetyl-Al and phosphorous acid Sample Material LOQ Apparent residues [mg/kg] [mg/kg]
fosetyl-AI phospho- fosetyl-Al phospho-rous acid rous acid Hofchen 0.05 0.05 < 10% LOQ < 20 /o LOQ
Laacher Hof 0.05 0.05 < 10% LOQ < 10% LOQ
3.3 Linearity of the Detectors and Matrix Effects The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using 15 standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L.
Experimental details can be found in Chapter 2.4.
In each chromatogram, the measured peak area of fosetyl-Al or phosphorous acid is plotted 20 versus the corresponding concentration of respectively fosetyl-Al or phosphorous acid contained in each standard solution, in order to obtain calibration curve of the form :
y = ax+b (1/x weighting) where : y = peak area, x = concentration in injected standard solution The results of the determination of detector response for LC/MS/MS are summarised inTable 35.
Table 35: Summary of the determination of detector linearity for LC/MS/MS.
phosphorous Detection Parameter fosetyl-Al acid LC/MS/MS Linear range [pg/L] 0.25 - 25 0.25 - 25 _...
...............................................................
...............................................................................
.................... ..................................
.................................................. ....................
............ _........ ................ _......... _......
No. of concentrations 7 or 8 7 or 8 ........................ ................ ................. _..... .......
............. _..._.._..._....................................
_............................. ........... ..................................
.... ....................... _.................... .................
_..................................................................
No. of injections 1 1 ...................................................... .......
_.............................. .............._.. .................
_............... _............. ..................... .......
................. .......................... ....................
_............... ............. _...............
.................................... _..................
1/x weighted 1/x weighted Model linear regression linear regression Correlation coefficient (R) 0.9999 - 0.9996 for standards prepared in solvent .......................................... _.......... _........... ._....
__.._................................
.................................................
.................................. _...... .............. e.
........................ .__................
_............................................................
Correlation coefficient (R) >_ 0.9997 0.9999 for matrix matched standards An excellent linear correlation between the injected amount of the analytes and the detector responses of LC/MS/MS was observed for standards in the range of 0.25 to 25 pg/L for both compounds, using either standards prepared in solvent or matrix matched standards.
The occurrence of matrix effects was monitored.
The results are shown in Table 36 and Table 37.
Table 36: Matrix effect evaluation for fosetyl-Al FL : Fortification Level Measurement using Number FL Standards in pure Matrix matched Sample Material of Values [mg/kg] ( ) solvent standards n Mean [%] RSD [%] Mean [%] RSD [%]
0.05 5 72 2.7 81 3.8 0.05 5 72 2.7 81 3.8 Hofchen 0.5 5 78 1.1 78 3.2 0.05 5 71 2.3 67 5.7 Laacher Hof 0.5 5 80 1.4 76 5.8 Table 37: Matrix effect evaluation for Phosphorous acid FL: Fortification Level Measurement using Number FL Standards in pure Matrix matched Sample Material of Values [mg/kg] (n) solvent standards Mean [%] RSD [%] Mean [%] RSD [%]
0.05 5 91 3.2 76 10.0 Hofchen 0.5 5 85 2.3 77 3.9 0.05 5 84 9.0 72 14.4 Laacher Hof 0.5--t 5 84 2.0 78 3.1 The results presented in the two previous Tables 36 and 37 show that :
- no significant difference is observed when the measurement of fosetyl-Al is established using either standards prepared in solvents, or matrix matched standards.
- the measurement of phosphorous acid is better (higher mean recoveries and lower RSD found) when it is established using standards prepared in solvents, instead of using matrix matched standards.
For all these reasons, we advice to use standards prepared in solvents.
3.4 Limit of Quantification and Recovery Experiments The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of ~ 20% could be obtained.
The LOQ
was set at 0.050 mg/kg for each compounds in soils samples.
To validate the method for these matrices, control samples were fortified with a defined amount of fosetyl-Al and phosphorous acid prior to analysis.
3.5 Recovery Rates The detailed recovery results obtained are listed in Tables 38 and 39.
All results given in Tables 38 and 39 have been obtained by using standards prepared in solvents and the quantifier ion (see 3.3.2).The results obtained with the confirmatory transition are given in Appendix 9.
Table 38: Recovery rates obtained for fosetyl-Al, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [%] [%]
0.05 Hofchen 75 71 70 72 73 72 2.7 0.05 Laacher Hof 70 72 71 74 70 71 2.3 mean of all 0.05 mg/kg single values 72 2.4 0.5 Hofchen 79 79 79 77 78 78 1.1 0.5 Laacher Hof 80 80 79 78 81 80 1.4 mean of all 0.5 mg/kg single values 79 1.5 mean of all Hofchen samples 75 4.7 mean of all Laacher Hof samples 76 6.0 overall mean 75 5.3 Table 39:Recovery rates obtained for Phosphorous acid, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [%] [%]
0.05 Hofchen 95 90 87 91 91 91 3.2 0.05 Laacher Hof 98 80 82 81 81 84 9.0 mean of all 0.05 mg/kg single values 88 7.3 0.5 Hofchen 87 84 86 82 84 85 2.3 0.5 Laacher Hof 84 83 84 83 87 84 2.0 mean of all 0.5 mg/kg single values 84 2.0 mean of all Hofchen samples 88 4.6 mean of all Laacher Hof samples 84 6.2 overall mean 86 5.6 The obtained recovery rates are summarised below in Table 40.
In total 20 recovery rates were determined for each compound.
Table 40: Summary of the recovery data for the determination of accuracy and repeatability;
RSD: relative standard deviation Phosphorous Number Parameter Fosetyl-Al acid of values n Single recoveries [%] 70 - 81 80 - 98 20 Mean recoveries per fortification level [%] 72 - 79 84 - 88 10 Accuracy Mean recoveries per kind of soils [%] 75 - 76 84 - 88 10 Overall mean [%] 75 86 20 RSD per fortification level [%] 1.5 - 2.4 2.0 - 7.3 10 Repeatability RSD per kind of soils [%] 4.7 - 6.0 4.6 - 6.2 10 Overall RSD [%] 5.3 5.6 20 The previous table shows that :
The single recovery rates were in the range of 70 to 81 % for fosetyl-Al and of 80 to 98 % for phosphorous acid. All mean recoveries rates were in the range of 70 to 110 %.
All RSD were well below 20 %.
4 Evaluation and Discussion The presented residue analytical method modification 00974/M001 was validated for the determination of residues of fosetyl-Al and its metabolite (phosphorous acid) in soils by LC/MS/MS.
The residues of fosetyl-Al and its metabolite (phosphorous acid) are extracted from the soil samples by shaking with ammonia buffer solution. This extract is then treated with a cationic resin and a final dilution is done before the analysis by LCMSMS. The residues are quantified by HPLC using an Hypercarb column and detected by tandem mass spectrometry with electrospray ionisation. The quantification was done by an external standardisation using standards prepared in pure solvent.
The validation set included the determination of the detector linearity, the limit of quantification and the accuracy of the method.
The linearity of the detector used was tested for fosetyl-Al and phosphorous acid using standards in solvent and matrix matched standards.
The linearity was tested by injecting standards of fosetyl-Al and phosphorous acid at concentrations between 0.25 and 25 pg/L. The detector response was linear in these ranges.
The occurrence of matrix effects was monitored - no significant difference is observed when the measurement of fosetyl-Al is established using either standards prepared in solvents, or matrix matched standards ;
- the measurement of phosphorous acid is better (higher mean recoveries and lower RSD found) when it is established using standards prepared in solvents, instead of using matrix matched standards.
For all these reasons, we advice to use standards prepared in solvents.
The apparent residues for all control samples were below 20% of the LOQ for each compound, i.e. < 0.01 mg/kg.
The limit of quantification (LOQ) was defined as the lowest fortification level where a mean recovery within the range of 70 to 110% and an RSD of D 20% could be obtained.
The LOQ
was set at 0.050 mg/kg for each compounds in soils samples.
The accuracy of the method can be assessed on the basis of the determined recovery rates.
The single recovery rates were in the range of 70 to 81 % for fosetyl-Al and of 80 to 98 % for phosphorous acid. All mean recoveries rates were in the range of 70 to 110 %.The accuracy of the method fulfils the requirements for residue analytical methods which demand that the mean recoveries for each fortification level should be in the range of 70-110%.
The precision and repeatability of the method can be assessed on the basis of the determined relative standard deviations (RSD) for the mean values of the recovery rates.
All RSD were well below 20 %. Thus the precision and repeatability of the method can be considered acceptable.
All results of the method validation are in accordance with the general requirements for residue analytical methods, so this method modification has been validated successfully.
Note : during analysis, for each sample set, it is necessary to do a blank reagent without soil sample to be sure that no phosphorous acid contamination (< 30% LOQ) coming from sample preparation is found.
Remarks :
= standard laboratory glass consumable should be cleaned with only detergents containing no phosphate and rinsed with water and acetone.
To avoid any contamination, the use of disposable laboratory consumable is strongly advised.
= Before start of validation / measurements equipment / chemicals should be tested for any residues of phosphorous acid.
= If some contamination is observed, see if the use of special HPLC vials (e.g.
polypropylene vials, Agilent, art. 5182-0567) can be helpful to reduce the background for phosphorous acid.
Appendix 7 Flow Diagram of Residue Method 00974/M001 Soil sample preparation procedure Main point :for each set of sanzples, it is necessary to do a blank reagent witliout soil sample to be sure that no H3P03 contamination (< 30% LOQJ
coniing from sample preparation is found (that is why disposable consumables are used) 20.0 g of soil sample into 125 mL polypropylene bottle (Add here 100,uL of the fortifying solution for LOQ recoveries or 100,uL of the fortifying solution for IOLOQ recoveries) +
30 mL of ammonia buffer solution Mechanical agitation (30 minutes) at ambient temperature Centrifugation (5 minutes at 3600rpm at -5 C) Bottom + 30 ml of ammonia buffer solution Put the floating into a weighted I disposable 250 mL polypropylene Mecltanical agitation ( 30 bottle where about 100 g of acidified minutes) at ambient temperature water at 0.5%formic acid were ~ already poured Centrifugation (5 minutes at 3600rpin at -5 C) Floating Make-up to 200 g with H20 at 0. 5% HCOOH, using Pasteur pipette : Extract A
Weigla 3 g of waslied AG 50W-X8 resin into a conical centrifuge tube Transfer about 5 mL of Extract A into this centrifuge tube, using disposable pipette Mecizanichal agitation for J minutes at anibient temperature Then centrifuge (5 minutes at - 6000 rpm - ambient):
the supernatant obtained corresponds to Extract B
Dilute 10 times the extract B in H20 + 0.5% xcooH = Final Extract for LCMSMS
If necessary to dilute the Final Extract due to concentration outside the calibration curve : use H20 + 0.5% HCOOH
Remark : - means 'around '. Study : 05-17 Appendix 8 Details on LC-MS/MS conditions Comment:
Synchronization Mode: LC Sync Auto-Equilibration: Off Acquisition Duration: 10min1sec Number Of Scans: 455 Periods In File: 1 Acquisition Module: Acquisition Method Software version Analyst 1.4 MS Method Properties:
Period 1:
--------------Scans in Period: 455 Relative Start Time: 0.00 msec Experiments in Period: 1 Period 1 Experiment 1:
----------------------------Scan Type: MRM (MRM) Polarity: Negative Scan Mode: N/A
Ion Source: Turbo Spray Resolution Q1: Unit Resolution Q3: Unit Intensity Thres.:0.00 cps Settling Time: 0.0000 msec MR Pause: 5.0070 msec MCA: No Step Size: 0.00 amu Quantifier transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 78.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -22.00 -22.00 CXP -5.00 -5.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 80.90 200.00 DP -45.00 -45.00 (fosetyl-Al) CE -16.00 -16.00 CXP -1.00 -1.00 Confirmatory transitions:
Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 80.90 62.90 400.00 DP -55.00 -55.00 (phosphorous acid) CE -38.00 -38.00 CXP -1.00 -1.00 Q1 Mass (amu) Q3 Mass (amu) Dwell(msec) Param Start Stop 108.90 62.90 300.00 DP -45.00 -45.00 (fosetyl-AI) CE -38.00 -38.00 CXP -5.00 -5.00 Parameter Table (Period I Experiment 1):
CAD: 6.00 CUR: 15.00 GS1: 40.00 GS2: 60.00 TEM: 650.00 ihe: ON
IS: -4500.00 EP -10.00 Agilent 1100 LC Pump Method Properties :
Pump Model: Agilent 1100 LC Binary Pump Minimum Pressure (psi): 0.0 Maximum Pressure (psi): 5801.0 Dead Volume (pl): 40.0 Maximum Flow Ramp (ml/min2): 100.0 Maximum Pressure Ramp (psi/sec): 290.0 Step Table:
Step Total Time(min) Flow Rate(pl/min) A(%) B(%) 0 0.00 200 55.0 45.0 1 10.00 200 55.0 45.0 Left Compressibility: 50.0 Right Compressibility: 115.0 Left Dead Volume (pl): 40.0 Right Dead Volume (NI):40.0 Left Stroke Volume (pl): -1.0 Right Stroke Volume (pI): -1.0 Left Solvent: Al (methanol + 2% formic acid) Right Solvent: B2 (water + 2% formic acid) CTC PAL Autosampler Method Properties :
Loop Volumel (pl): 50 Loop Volume2 (pl): 100 Injection Volume (NI): 100.000 Method Description:
Syringe: 250u1 Analyst LC-Inj Air Volume (pl) 0 Pre Clean with Solvent 1() 2 Pre Clean with Solvent 2() 1 Pre Clean with Sample () 0 Filling Speed (pl/s) 50 Filling Strokes () 0 Inject to LC Vlvl Injection Speed (pl/s) 50 Pre Inject Delay (ms) 500 Post Inject Delay (ms) 500 Post Clean with Solvent 1() 3 Post Clean with Solvent 2() 2 Valve Clean with Solvent 1() 2 Valve Clean with Solvent 2O 1 Gas pressure Autosampler CTC Analytics HTS Pal (GLP n 1303) N2 4 bar Peltier rack 10 C
Air GSI/GS2 gas 7 bar Wash solvent 1: H20 + 0.5%HCOOH
Air Exhaust gas 4 bar Wash solvent 2: MeOH
Pumps Analytical LC pump.:
Binary 1 pump Agilent 1100 (GLP n 1296):
Al = Methanol + 2% Formic Acid Valco valve used Column selector used B2 = H20 + 2% Formic Acid GLP n 1289 GLP n 1356 Source GLP n 1291 Probe TurbolonSpray Pump for making-up solvent : GLP n 1288 Horizontal Position 7 (x axis) Vertical Position 7 axis) Ca illar exit 1 mm Mass Spectrometer API 4000 Device GLP n 1292 Binary 2 pump Agilent 1100 (GLP n 1297):
A2 = H20 + 2% Formic Acid Column : at room temperature B2 = Acetonitrile Precolumn : none Column : SMAR 68-1 Thermo Hypercarb 100 x 2.0mm 5 m Appendix 9 Results obtained with confirmatory transitions All results in Tables 41 and 42 have been obtained by using standards prepared in solvents.
Table 41: Recovery rates obtained for Fosetyl-Al, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [%] [%]
0.05 Hofchen 77 73 72 76 74 74 2.8 0.05 Laacher Hof 72 72 76 76 74 74 2.7 mean of all 0.05 mg/kg single values 74 2.6 0.5 Hofchen 79 79 80 76 78 78 1.9 0.5 Laacher Hof 80 80 79 79 81 80 1.0 mean of all 0.5 mg/kg single values 79 1.7 mean of all Hofchen samples 76 3.6 mean of all Laacher Hof samples 77 4.4 overall mean 77 3.9 Table 42: Recovery rates obtained for Phosphorous acid, RSD: relative standard deviation Fortification Soil Single Values [%] Mean RSD
[mg/kg] [ /a] [%]
0.05 Hofchen 92 87 85 87 85 87 3.3 0.05 Laacher Hof 87 75 78 73 79 78 6.8 mean of all 0.05 mg/kg single values 83 7.4 0.5 Hofchen 86 85 85 81 84 84 2.3 0.5 Laacher Hof 83 83 83 82 86 83 1.8 mean of all 0.5 mg/kg single values 84 2.0 mean of all Hofchen samples 86 3.3 mean of all Laacher Hof samples 81 5.6 overall mean 83 5.3 All results obtained above with confirmatory transition comply with European requirements.
Appendix 10 Soil characterisation Soil Hofchen Soil Hofchen, plot 4011: 0- 30 cm soil layer pH (in CaC12 solution) 6.7 pH (in H20) 7.4 Organic Carbon [%] 0.92 Organic Matter [%] * 1.58 Cation Exchange Capacity 12.4 [meq / 100 g dry soil]
max. Water Holding Capacity 39.4 [g / 100 g dry soil]
Textural Description according to USDA
Fraction [%]
Clay 19.4 (<0.002 mm) Silt 76.3 (0.002-0.050 mm) Sand 4.3 (0.050-2.000 mm) Soil type: silt loam * Organic matter = Organic carbon x 1.72 Soil Laacher Hof Soil Laacher Hof, plot 712/718: 0- 30 cm soil layer pH (in CaCI2 solution) 6.8 pH (in H20) 7.4 Organic Carbon [%] 1.20 Organic Matter [%] 2.06 Cation Exchange Capacity 9.8 [meq / 100 g dry soil]
max. Water Holding Capacity 37.9 [g/100gdry soil]
Textural Description according to USDA
Fraction [%]
Clay 12.0 (<0.002 mm) Silt 18.3 (0.002-0.050 mm) Sand 69.7 (0.050-2.000 mm) Soil type: sandy loam * Organic matter = Organic carbon x 1.72
Claims (45)
1. Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.00005 mg/kg of a sample, comprising the following steps:
- preparation of the sample;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
- preparation of the sample;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
2. Method according to Claim 1, comprising a step consisting of dilution of the sample prepared.
3. Method according to either of Claims 1 and 2, for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.000005 mg/kg of sample.
4. Method according to any one of Claims 1 to 3, for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.0000005 mg/kg of sample.
5. Method according to any one of Claims 1 to 4, for which the sample is chosen from plant tissues ; water ; soils ; animal products or tissues ; air ; agrofood products, and human body fluids such as blood and urine.
6. Method according to any one of Claims 1 to 5, for which the sample is chosen from a plant matrix with a high water content, a plant matrix with an acidic pH, a dry plant matrix, a fatty plant matrix ; mineral water, underground water, mains water or surface water ; milk, eggs, liver, kidneys, fats, muscle ; converted agrofood products ; human body fluids such as blood and urine.
7. Method according to any one of Claims 1 to 6, for which the preparation is chosen from an extraction for plant tissues ; soils ; animal products or tissues and converted agrofood products ; optional concentration for water and trapping for air.
8. Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.005 mg/kg of a water sample, comprising the following steps:
- preparation of the water sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
- preparation of the water sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
9. Method of analysis according to Claim 8, for the analysis of amounts of less than or equal to 0.00005 mg/kg.
10. Method of analysis according to either of Claims 8 and 9, for the analysis of amounts of less than or equal to 0.0000005 mg/kg.
11. Method according to any one of Claims 8 to 10, for which the sample is chosen from mineral water, underground water, mains water or surface water.
12. Method according to any one of Claims 8 to 11, for which the preparation is an optional concentration of the water.
13. Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 1 mg/kg of a plant tissue sample, comprising the following steps:
- preparation of the plant tissue sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
- preparation of the plant tissue sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
14. Method of analysis according to Claim 13, for the analysis of amounts of less than or equal to 0.01 mg/kg.
15. Method of analysis according to either of Claims 13 and 14, for the analysis of amounts of less than or equal to 0.001 mg/kg.
16. Method according to any one of Claims 13 to 15, for which the sample is chosen from a plant matrix with a high water content, a plant matrix with an acidic pH, a dry plant matrix and a fatty plant matrix.
17. Method according to any one of Claims 13 to 16, for which the preparation is an extraction of the plant tissue.
18. Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 5 mg/kg of a soil sample, comprising the following steps:
- preparation of the soil sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
- preparation of the soil sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
19. Method of analysis according to Claim 18, for the analysis of amounts of less than or equal to 0.05 mg/kg.
20. Method of analysis according to either of Claims 18 and 19, for the analysis of amounts of less than or equal to 0.005 mg/kg.
21. Method according to any one of Claims 18 to 20, for which the sample is chosen from a clayey, sandy or chalky soil.
22. Method according to any one of Claims 18 to 21, for which the preparation is an extraction of the soil sample.
23. Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.1 mg/m3 of an air sample, comprising the following steps:
- preparation of the sample;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
- preparation of the sample;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
24. Method according to either of Claims 23 and 24, for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.01 mg/m3 of sample.
25. Method according to either of Claims 23 and 24, for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.001 mg/m3 of sample.
26. Method according to any one of Claims 23 to 25, for which the preparation is a trapping.
27. Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.00005 mg/kg of a sample of a human body fluid, comprising the following steps:
- preparation of the sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
- preparation of the sample ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
28. Method according to either of Claims 27 and 28, for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.000005 mg/kg of sample.
29. Method according to either of Claims 27 and 28, for analyzing one or more pesticidal compounds present in amounts of less than or equal to 0.0000005 mg/kg of sample.
30. Method according to any one of Claims 27 to 29, for which the sample is chosen from human blood and human urine.
31. Method for analyzing one or more pesticidal compounds present in amounts of less than or equal to 1 mg/kg of a sample of animal products or tissues, comprising the following steps:
- preparation of the sample of animal products or tissues ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
- preparation of the sample of animal products or tissues ;
- optional dilution of the sample prepared ;
- direct analysis of the optionally diluted sample by high performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS).
32. Method of analysis according to Claim 31, for the analysis of amounts of less than or equal to 0.01 mg/kg.
33. Method of analysis according to either of Claims 31 and 32, for the analysis of amounts of less than or equal to 0.001 mg/kg.
34. Method according to any one of Claims 31 to 33, for which the sample is chosen from milk, eggs, liver, kidneys, fats and muscle.
35. Method according to any one of Claims 31 to 34, for which the preparation is an extraction of the animal products or tissues.
36. Method according to any one of Claims 13 to 17, for which the plant tissues are replaced with converted agrofood products.
37. Method according to any one of Claims 1 to 36, comprising a step consisting of dilution of the sample prepared.
38. Method according to any one of Claims 1 to 37, for the simultaneous analysis of several pesticidal compounds.
39. Method according to any one of Claims 1 to 38, for the analysis of one or more fungicidal, herbicidal, insecticidal or growth-regulating compounds.
40. Method according to any one of Claims 1 to 39, for the analysis of fungicidal compounds chosen from phosphorous acid or a derivative thereof ; phosphonic acid or a derivative thereof.
41. Method according to Claim 40, for the analysis of fosetyl or of one or more salts thereof.
42. Method according to Claim 41, for the analysis of fosetyl-Al.
43. Method according to any one of Claims 1 to 42, for the simultaneous analysis of phosphorous acid and of fosetyl-Al.
44. Method according to any one of Claims 1 to 43, for which the dilution is carried out in an aqueous solvent, which may be acidified, or in an organic solvent, which may be acidified, or in a mixture of such solvents.
45. Method according to Claim 44, for which the aqueous solvent comprises an acid chosen from formic acid, acetic acid or trifluoroacetic acid, or the organic solvent is chosen from acetonitrile or methanol.
Applications Claiming Priority (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP05356015.7 | 2005-01-25 | ||
| EP05356015A EP1684068A1 (en) | 2005-01-25 | 2005-01-25 | Analysis method for pesticide compounds |
| EP05356031.4 | 2005-02-11 | ||
| EP05356031 | 2005-02-11 | ||
| EP05356216.1 | 2005-12-16 | ||
| EP05356216 | 2005-12-16 | ||
| PCT/EP2006/001433 WO2006079566A1 (en) | 2005-01-25 | 2006-01-23 | Method of analyzing phosphorous acid, fosetyl-al or both simultaneously |
Publications (2)
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|---|---|
| CA2595465A1 true CA2595465A1 (en) | 2006-08-03 |
| CA2595465C CA2595465C (en) | 2017-09-26 |
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|---|---|---|---|
| CA2595465A Expired - Fee Related CA2595465C (en) | 2005-01-25 | 2006-01-23 | Method of analyzing phosphorous acid, fosetyl-al or both simultaneously |
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|---|---|
| US (1) | US8122760B2 (en) |
| EP (1) | EP1844327A1 (en) |
| JP (1) | JP5028275B2 (en) |
| KR (1) | KR101276987B1 (en) |
| AR (1) | AR052561A1 (en) |
| AU (1) | AU2006208702C1 (en) |
| BR (1) | BRPI0606239A2 (en) |
| CA (1) | CA2595465C (en) |
| CR (1) | CR9330A (en) |
| GT (1) | GT200600026A (en) |
| IL (1) | IL184721A0 (en) |
| MA (1) | MA29515B1 (en) |
| MX (1) | MX2007008773A (en) |
| WO (1) | WO2006079566A1 (en) |
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| ES2436744T3 (en) * | 2007-08-24 | 2014-01-07 | Emd Millipore Corporation | System to derive a liquid chromatography eluent |
| JP5227556B2 (en) * | 2007-09-06 | 2013-07-03 | 株式会社日立製作所 | Analysis equipment |
| US7987701B2 (en) * | 2008-05-07 | 2011-08-02 | University Of Memphis Research Foundation | Real-time, on-line analysis for the quantification of total haloacetic acid and trihalomethane species in drinking water supplies |
| EP2850643B1 (en) * | 2012-05-18 | 2020-01-22 | DH Technologies Development Pte. Ltd. | Method and system for introducing make-up flow in an electrospray ion source system |
| SI3221692T1 (en) * | 2014-11-18 | 2021-11-30 | Vertex Pharmaceuticals Inc. | Process of conducting high throughput testing high performance liquid chromatography |
| CN105675772B (en) * | 2016-04-13 | 2018-03-23 | 山东大学 | Weaken the method for matrix effect in a kind of LC-MS detection technique |
| CN106645539B (en) * | 2017-03-10 | 2018-04-03 | 中国热带农业科学院分析测试中心 | A kind of method of ultra performance liquid chromatography tandem mass spectrum detection phosethyl-Al |
| CN112697915B (en) * | 2020-12-17 | 2022-09-02 | 青岛海关技术中心 | Method for measuring residual amount of phosphorous acid in plant-derived food |
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| US4904595A (en) * | 1985-06-14 | 1990-02-27 | Health Research Incorporated | Epithelial cell line useful in the detection of dioxinlike compounds and methods of making and using same |
| US5854084A (en) * | 1996-07-12 | 1998-12-29 | Biotraces, Inc. | Enhanced chromatography using multiphoton detection |
| US6637438B1 (en) * | 1997-04-21 | 2003-10-28 | Kerry Scott Lane | Method for assay and removal of harmful toxins during processing of tobacco products |
| US6058940A (en) * | 1997-04-21 | 2000-05-09 | Lane; Kerry Scott | Method and system for assay and removal of harmful toxins during processing of tobacco products |
| US6749811B2 (en) * | 1998-04-28 | 2004-06-15 | The Johns Hopkins University | Molecularly imprinted polymer solution anion sensor |
| US6541272B1 (en) * | 1998-12-31 | 2003-04-01 | New Jersey Institute Of Technology | Pulse introduction membrane extraction apparatus and method for separating and analyzing at least one component in a fluid contaminated with the at least one component |
| US6680203B2 (en) * | 2000-07-10 | 2004-01-20 | Esperion Therapeutics, Inc. | Fourier transform mass spectrometry of complex biological samples |
| EP1352054A2 (en) * | 2000-10-30 | 2003-10-15 | Pharmacia Corporation | Aspergillus ochraceus 11 alpha hydrolase and oxidoreductase |
| CA2535526C (en) * | 2003-08-11 | 2015-09-29 | Diversa Corporation | Laccases, nucleic acids encoding them and methods for making and using them |
| DE102004063633B4 (en) * | 2004-12-28 | 2011-12-15 | Polymerics Gmbh | Use of a sorbent for solid phase extraction (SPE) |
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- 2006-01-23 US US11/883,036 patent/US8122760B2/en not_active Expired - Fee Related
- 2006-01-23 AU AU2006208702A patent/AU2006208702C1/en not_active Ceased
- 2006-01-23 KR KR1020077019301A patent/KR101276987B1/en not_active IP Right Cessation
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| Publication number | Publication date |
|---|---|
| GT200600026A (en) | 2006-11-07 |
| AU2006208702C1 (en) | 2011-12-08 |
| KR101276987B1 (en) | 2013-06-25 |
| IL184721A0 (en) | 2007-12-03 |
| JP2008528956A (en) | 2008-07-31 |
| AR052561A1 (en) | 2007-03-21 |
| AU2006208702A1 (en) | 2006-08-03 |
| MA29515B1 (en) | 2008-06-02 |
| JP5028275B2 (en) | 2012-09-19 |
| US8122760B2 (en) | 2012-02-28 |
| WO2006079566A1 (en) | 2006-08-03 |
| AU2006208702B2 (en) | 2011-03-31 |
| CA2595465C (en) | 2017-09-26 |
| KR20070103469A (en) | 2007-10-23 |
| BRPI0606239A2 (en) | 2009-06-09 |
| US20080257019A1 (en) | 2008-10-23 |
| EP1844327A1 (en) | 2007-10-17 |
| CR9330A (en) | 2008-03-27 |
| MX2007008773A (en) | 2007-09-12 |
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