CN104034565A - Pretreatment method for gas chromatography detection on chlorpyrifos-methyl in tea leaf - Google Patents

Abstract

The invention discloses a pretreatment method in pesticide residue detection, and in particular relates to a pretreatment method for gas chromatography detection on chlorpyrifos-methyl in tea leaves. The pretreatment method comprises the following steps: uniformly mixing a tea leaf sample to be detected with acetone according to a mass volume ratio of 1:2, performing ultrasonic wave extraction for more than 30 minutes, adding sodium chloride, uniformly oscillating, standing for 30minutes, taking the supernate, filtering by using anhydrous sodium sulfate, washing the anhydrous sodium sulfate by using acetone, collecting the acetone solution after washing, heating in water bath and drying in air to obtain residue, mixing triphenyl phosphate acetone solution of which the mass concentration is 0.1% with the residue till the residue is completely dissolved, filtering to obtain an available sample solution to be detected, and completing the treatment. The method disclosed by the invention is simple and feasible, ordinary reagents are adopted, the operability is high, practical operation comparison shows that due to addition of acetone, the sample solution is good in layering effect, the indexes such as the measurement accuracy, the precision and the sensitivity can all meet a relatively good effect, and an effective way is provided for standardization detection.

Description

A kind of pre-treating method for gas chromatographic detection tealeaves chlorpyrifos-methyl

Technical field

The present invention is the preprocess method in the residual detection of a kind of agriculture, especially a kind of pre-treating method for gas chromatographic detection tealeaves chlorpyrifos-methyl.

Background technology

Chlorpyrifos-methyl is a kind of organophosphorus insecticide of wide spectrum, by tagging, stomach toxicity and stifling all effective, without interior absorption, for preventing and treating the insect of storage cereal and the insect on various leaf class crop, also can be used to prevent and treat mosquito adult, fly class, aquatic larva and sanitary insect pest, in soil without lasting effect.

Chlorpyrifos-methyl is mainly to cause Neurotransmission to block by suppressing the activity of acetylcholinesterase in insect bodies, and then cause insect death, and chlorpyrifos-methyl also has obvious inhibiting effect to human erythrocyte membrane acetylcholinesterase, so various countries also limit the maximum residue limit of chlorpyrifos-methyl.

At present, the existing methods such as high performance liquid chromatography, Ultra Performance Liquid Chromatography tandem mass spectrum, gas chromatography-flame luminosity that adopt, for the chlorpyrifos-methyl in water body, cereal crops, fruit etc., carry out gas chromatographic detection, but for the chlorpyrifos-methyl in tealeaves, and the method for how to carry out corresponding pre-treatment, have no temporarily report.

Summary of the invention

The present invention aims to provide the stable pre-treating method for gas chromatographic detection tealeaves chlorpyrifos-methyl of simple, the upper machine measurement result of a kind of step.

Pre-treating method for gas chromatographic detection tealeaves chlorpyrifos-methyl of the present invention, comprises the steps:

Step 1, get Tea Samples to be detected and mix according to mass volume ratio 1:2 with acetone;

Step 2, solution carry out ultrasound wave extraction and are no less than 30 minutes;

Step 3, add sodium chloride, vibration evenly, standing 30 minutes;

Step 4, get supernatant, through anhydrous sodium sulfate, filter;

Step 5, employing acetone wash anhydrous sodium sulfate;

Acetone soln after step 6, collection washing, heating water bath is air-dry, obtains residue;

Step 7, to get mass concentration be this ester of tricresyl phosphate acetone soln of 0.1%, is mixed to residue dissolves completely with residue, and after filtration, the testing sample solution that must be available on the machine, is disposed.

In step 4, the thickness of anhydrous sodium sulfate layer is not less than 4 centimetres.

Method of the present invention is simple, all adopts conventional reagent, workable, through practical operation contrast, to find to add after acetone, sample solution layered effect is good, the indexs such as the accuracy of measuring, precision, sensitivity all can reach better effects, for the effective approach that provides is provided in standardization.

Accompanying drawing explanation

Fig. 1 is the gas chromatogram of chlorpyrifos-methyl standard solution.

Fig. 2 is the gas chromatogram of the testing sample solution testing result that is available on the machine.

Embodiment

Below in conjunction with embodiment, method of the present invention is illustrated.

For a pre-treating method for gas chromatographic detection tealeaves chlorpyrifos-methyl, first-selection, gets Tea Samples 5g to be detected, and 10ml mixes with acetone (analyzing pure).

Solution after mixing is carried out in ultrasonic washing instrument to ultrasound wave extraction, the time is no less than 30 minutes, through actual test, finds, if the time is too short, the actual amount detecting is less, affects the accuracy of final detection result, and result is as shown in table 2.

Table 1, ultrasound wave extraction time contrast

Add sodium chloride, vibration evenly, sodium chloride addition is no less than 1g, after standing 30 minutes, solution presents layering, now according to step 4, get the supernatant after layering, through anhydrous sodium sulfate layer, filter, for obtaining better filter effect, the thickness of anhydrous sodium sulfate layer is not less than 4 centimetres, and the present embodiment is 5 centimetres.

Adopt acetone 20ml, anhydrous sodium sulfate is washed, collect the acetone soln after washing, heating water bath is air-dry, obtains residue, 70 ℃ of bath temperatures.

Get mass concentration and be this ester of tricresyl phosphate acetone soln of 0.1%, be mixed to residue dissolve completely with residue, after filtration, the testing sample solution that must be available on the machine, is disposed.

In the present embodiment, to the testing sample solution that adopts above-mentioned pre-treating method to be disposed, simultaneously configuration concentration be 0.20,1.00,10.00,25.00, the chlorpyrifos-methyl standard solution of 100.00mg/L, adopt flame photometric detector (FPD) to detect, chromatographic column is selected Agilent (agilent) DB-35ms of company quartz capillary chromatographic column, 30m*0.25m*0.25m, initial 150 ℃ of column temperature, keep 2min, with 10 ℃/min speed, be warming up to 250 ℃, with 30 ℃/min speed, be warming up to 280 ℃ again, keep 5min; 220 ℃ of injector temperatures, 250 ℃ of detector temperatures, carrier gas, nitrogen, purity 99.999%, column flow rate 1.2ml/min; Hydrogen, flow velocity 75ml/min, air, flow velocity 100ml/min; Splitless injecting samples, sample size 1L.

By above-mentioned condition, to adopting this patent method to carry out the sample after pre-treatment, as shown in Figure 1, chlorpyrifos-methyl retention time is 10.82min to the gas chromatogram of chlorpyrifos-methyl standard solution, this ester of tricresyl phosphate 16.44min.The gas chromatogram of the testing sample solution testing result that tealeaves is available on the machine as shown in Figure 2.

Claims (2)

1. for a pre-treating method for gas chromatographic detection tealeaves chlorpyrifos-methyl, it is characterized in that comprising the steps:

Step 1, get Tea Samples to be detected and mix according to mass volume ratio 1:2 with acetone;

Step 2, solution carry out ultrasound wave extraction and are no less than 30 minutes;

Step 3, add sodium chloride, vibration evenly, be standingly no less than 30 minutes;

Step 4, get supernatant, through anhydrous sodium sulfate layer, filter;

Step 5, employing acetone wash anhydrous sodium sulfate;

Acetone soln after step 6, collection washing, heating water bath is air-dry, obtains residue;

Step 7, to get mass concentration be this ester of tricresyl phosphate acetone soln of 0.1%, is mixed to residue dissolves completely with residue, and after filtration, the testing sample solution that must be available on the machine, is disposed.

2. the pre-treating method for gas chromatographic detection tealeaves chlorpyrifos-methyl according to claim 1, is characterized in that: in step 4, the thickness of anhydrous sodium sulfate layer is not less than 4 centimetres.