WO2014087360A1

WO2014087360A1 - Method for detection of kerosene adulteration with extrinsic marker in gasoline, aviation turbine fuel and diesel

Info

Publication number: WO2014087360A1
Application number: PCT/IB2013/060655
Authority: WO
Inventors: Naduhatty SELAI RAMAN; Narayanam SESHUBABU; Dheer SINGH; Anurag Ateet Gupta; Santanam Rajagopal; Ravinder Kumar Malhotra
Original assignee: Indian Oil Corporation Limited
Priority date: 2012-12-06
Filing date: 2013-12-05
Publication date: 2014-06-12

Abstract

The present invention provides an accurate and cost effective method to detect adulteration of gasoline, aviation turbine fuel and diesel with an adulterant, by detecting an extrinsic marker and determining the concentration of the marker in adulterated gasoline and diesel fuels employing gas chromatography with or without mass spectroscopy. The disclosed invention primarily involves the extrinsic marker having organo sulfur molecule, or molecules bearing C-S bond, S- S bond, or both.

Description

METHOD FOR DETECTION OF KEROSENE ADULTERATION WITH EXTRINSIC MARKER IN GASOLINE, AVIATION TURBINE FUEL AND DIESEL

FIELD OF THE INVENTION

The present invention is related to a method for detection of adulteration in gasoline, aviation turbine fuel and diesel. More particular!}', the present invention relates to an accurate and cost effective method of detection of adulteration by kerosene in gasoline, aviation turbine fuel and diesel fuel.

BACKGROUND OF THE INVENTION

The crude oil is one of the important raw materials for the production of gasoline, diesel, kerosene and aviation turbine fuel, which are derived during the atmospheric distillation of crude oil. All over the globe, gasoline, aviation turbine fuel and diesel fuels are considered as high premium fuels due to their high production cost as compared to kerosene fuel, which is termed as low premium fuel, although all of them emanate from the crude oil.

Furthermore, products derived from crude oil can be considered as one of primary source of energy for industry and transportation. Primarily gasoline, aviation turbine fuel and diesel are used as transportation fuel due to their high energy content and ease of storage and carrying. Although gasoline and diesel fuels are obtained from crude oil during the distillation process, still they contain considerable amount of sulfur, nitrogen and aromatics compounds. As a result the emissions from such fuels are environmentally hazardous. Therefore, gasoline and diesel fuels need to be processed further by various treatments in order to meet desired fuel specifications prior to their use. Eventually, its production cost escalates.

In order to make fuels meeting the specifications as prescribed by environmental regulations, oil Finns invest enormously. However, there are instances where customers are deprived of high quality fuels because of the adulteration of the high premium grade fuels with low premium grade fuels. These adulterations are due to substantial price differential of gasoline and diesel as compared to kerosene, the price differential even further widens with the increasing cost of the crude oil.

I This adulteration of fuel not only increases pollution by emitting hydrocarbon (HC), carbon monoxide (CO), oxides of nitrogen (NOx), oxides of Sulfur (SOx), particulate matter (PM) and air toxin substances, but also deteriorates the quality of base transport fuel which further impedes the engines performance and other internals, eventually minimizes engine life. The problem gets further magnified for high performance modem engines. Fuel adulteration though being an illegitimate act, is increasing day by day due to inadequate methods available to detect the fuel adulteration.

The existing methodology for detecting kerosene content in gasoline and diesel by conventional volumetric distillation is highly complex due to partial overlapping of kerosene fraction in both gasoline and diesel fractions. Although there are some critical properties which are different between these fuels such as density, kinematic viscosity, flash point, volumetric distillation methods, still these properties do not invoke any marked difference particularly for low kerosene concentrations in gasoline and diesel fuels. Hence the detection of kerosene content, preferably 0.5 vol% or higher in gasoline and diesel has remained an intriguing challenge.

CA 2773774 patent discloses the method of using marker namely azadipyrromethene dyes, dipyrromethene dyes, and their combination, pre mixed with petroleum products. The pre mixed dye was then analyzed by absorption spectroscopic techniques in order to identify the presence of secret dye. The absorption radiation by the sample is directly proportional to the concentration of the marker. Though the disclosed marker has shown the advantage of detecting the kerosene adulteration in gasoline or diesel, still, the synthesis of marker is difficult as it involves multi steps and tedious work up procedures.

US Patent No. 5358873 disclosed the method of mixing the known concentration of Rhodamine B base marker dye (containing mixture of organic bases such as Rhodamine B base and pyrrolidinone in different proportions) in gasoline pool. If any undesired fuel is mixed with such gasoline and the resulted gasoline sample is subjected to treatment with silica in vial, the silica turns into red color indicating the adulteration in the fuel. However, the described method deals the adulteration of reformate gasoline with non-reformate gasoline fuels only, while this method does not cover the detection of kerosene adulteration in gasoline or diesel. US patent No. 4918020 claims a method for analyzing marker dyes in automotive gasoline. In this method, solid-phase extraction of fuel sample is carried out onto a packed column followed by the formation of a colored complex in the column by reacting with a separated marker dye of color-forming reagent. The color intensity of the colored complex is then determined to indicate the concentration of the marker dye in the fuel sample. The disclosed method is rather critical to apply practically as the method involves the solid phase extraction of marker and determine its presence by spectroscopic methods followed by reacting with color forming reagents,

US Patent No. 5229298 disclosed a method of analyzing nitrogen bearing marker dye concentration in liquid fuels selected from the group consisting of I-(4-morphiolino)-3-alpha- napthylamino-propane and l-(4-morpholino)-3-beta napthylamino-propane. The concentration of marker has been analyzed by gas chromatography equipped with nitrogen phosphorescence detector using trioctyl amine as internal standard. However, the markers disclosed here are prepared by various expensive protocols and method deals only with the detection of adulteration in gasoline fuels and not in the diesel fuels.

US Patent No. 5980593 disclosed the method to mark the fuels and identify the marker adopting suitable spectroscopic technique. The disclosed marker is coumarine derivative (1 ,2- benzopyrene) having the linear C1-C18 or branch of C5-C10 bearing the ester functional group. Further the marker detection can be achieved by base extraction followed by UV fluorescent spectroscopy. The coumarin derivative markers are readily soluble in petroleum fuels due to the presence of ester functional group, and therefore claimed the advantage of marker stability in petroleum fuels. However the marker requires suitable liquid carrier in order to transport it for end-use. In addition, the disclosed coumarine derivative markers are synthesized from the respective acid chlorides by esterification which is a expensive multistep synthesis protocol.

US Patent No. 7858373 discloses various planar six membered cyanurate, isocyanurate or 1 ,3,5- triazine derivative markers to detect the adulteration in various liquid fuels such as commercial gasoline, diesel, bio diesel and ethanol blended gasoline. The presence of marker is determined by mass spectroscopy, as it displays the presence of characteristic m/z peaks of respective markers. However the disclosed markers are synthesized by various steps and hence marker is expensive and requires skilled chemist to understand the symmetry of the molecules and to analyze the data generate by the sophisticated mass spectroscopy. US Patent No. 5958780 discloses a method of introducing two miscible markers such as cyanobenzene as first marker and its isotopic molecule as second marker into high premium gasoline fuel. The marker has been chosen in such a way that, these markers are capable of absorbing both visible and I radiation. The absorption spectra of the marker are analyzed to determine the concentration of first and second marker in the marked liquid fuels. Any deviation measured in concentration of marker in marked fuel indicates the presence of adulterant fuels. The disclosed method appears to be simple but the markers are not environmentally friendly and are hazardous to health as the marker bears toxic cyano group.

Patent publication WO 2012/050844, discloses the method of using single or multiple fluorescent taggant variants having the emission fluorescence range between 500-900 ran, by doping them in the liquid fuels and analyzing their concentration by customized spectroscopic methods. The disclosed method involves complex procedural methods to determine the concentration of taggant, therefore highly skilled technician required to analyze the fluorescent taggant in fuel.

Of late, most of detection methods mvolve the use of expensive synthetic dye or fluorescent based chemical markers in fuel and therefore applies the physicochemical or spectroscopic methods of determining their concentration. In addition the majority of markers reported in literature are synthesized by various expensive and tedious synthesis protocols. As a result of it, marker cost has become expensive as its synthesis requires expensive reagents and tedious work up procedures. Furthermore, these dye markers directly marked to gasoline or diesel fuels of known concentration, then determine the precise concentration by using appropriate spectroscopic methods unveils the presence of marker. Thereafter, if any deviation in marker concentration of analyzed fuel would notify the presence of adulterant in gasoline or diesel. Direct marking of gasoline or diesel is not suggested due to the presence of various multifunctional additives in high premium fuels, therefore their activity may retard due to presence of marker. Therefore, detection of low scale fuel adulteration still remains to be explored.

With the growing drive to deter fuel adulteration and to offer more authenticate fuels, more improved methods are yet to be identified. In view of inadequate methods available for detection of kerosene content in high premium fuels particularly for those fuels having kerosene content 0.5vol% or higher, a suitable protocol needs to be developed which can detect the kerosene content in high premium fuels in relatively simple manner. Accordingly systematic study was conducted in order to develop a facile protocol to detect the kerosene content in gasoline and diesel fuels.

SUMMARY OF THE INVENTION

The present invention provides a method to detect adulteration of gasoline, aviation turbine fuel and diesel with an adulterant, by detecting an extrinsic marker and determining the concentration of the marker in adulterated gasoline and diesel fuels employing gas chromatography with or without mass spectroscopy. The disclosed invention primarily involves the extrinsic marker having organo sulfur molecule, or molecules bearing C-S bond, S-S bond, or both.

The present invention provides a method of detecting an adulterant in gasoline, aviation turbine fuel or diesel, with the help of a marker, wherein the adulterant is kerosene.

In one aspect, the present invention provides a method of detecting kerosene adulteration in a fuel, the method comprising detecting the presence of an organo sulphur marker in the fuel, wherein the kerosene is pre-marked with said organo sulphur marker, and wherein the fuel is adulterated with said pre-marked kerosene in an amount of 0.5 vol% or more. In another aspect, the present invention provides a method of marking kerosene with an organo sulphur marker. The method comprises adding an organo sulphur compound to kerosene in an amount of 10 ppm to 100 ppm.

The present invention also provides a marked kerosene product, wherein the kerosene is marked with an organo sulphur marker of the present invention, in a concentration range of 10 ppm to 100 ppm.

In yet another aspect, the present invention provides a marker for detection of an adulterant in a fuel. The marker is selected from an organo sulfur compound containing C-S bond, S-S bond or both, and wherein the marker is added in an amount of 10 ppm to 100 ppm in the said adulterant. When the said marked adulterant is added in gasoline, aviation turbine fuel, or diesel, in an amount as low as 0.5 vol%, the presence of said adulterant can be detected in the adulterated fuel. In the present invention, the organo sulfur marker or the organo sulfur compound is a molecule or molecules bearing a C-S bond, S-S bond or both. The organo sulfur marker or the organo sulfur compound is selected from a group comprising of dialkyl/diaryl/alkyl-aryl sulphide and dialkyl/diaryl/alkyl-aryl di sulphide compounds, which includes dimethyl sulfide, dimethyl disulfide, diethyl sulfide, diethyl disulphide, diisopropyl disulphide, di-tert-butyl disulphide, dibenzyl sulphide, dibenzyl disulphide, thioanisole, thiophene, tetrahydrothiophene, methyl substituted thiophenes, benzothiophene, mono, di and tri methyl substituted benzothiophenes, polysulphides or mixtures thereof,

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Fig 1 : shows GC-SCD profiles of kerosene (marker-1) adulterated high sulphur Gasoline fuels; Fig 2: shows GC-SCD profiles of kerosene (marker-1) adulterated high sulphur diesel fuels;

Fig 3: shows GC-SCD profiles of kerosene (Marker-1) adulterated low sulphur Gasoline fuels;

Fig 4: shows GC-SCD profiles of kerosene (marker-1) adulterated low sulphur diesel fuels;

Fig 5: shows Marker (2) doped Kerosene, 1 %Kero-Diesel and 1 %Kero-Gasoline;

Fig : shows Marker (3) doped Kerosene, l %Kero-Diesel and l %Kero-Gasoline; Fig 7: shows Marker (4) doped Kerosene, l %Kero-Diesel and l %Kero-Gasoline;

Fig 8: shows Marker (5) doped Kerosene, 1 %Kero-Diesel and l %Kero-Gasoline;

Fig 9: shows GC-SCD profiles of A.C treated marked kerosene, 1% A.C treated marked kerosene in MS, and 1 % marked kerosene in MS (Gasoline);

Fig 10: shows GC-SCD profiles of A.C treated marked kerosene, lvol% A.C treated marked kerosene in Diesel, and lvol% marked kerosene in Diesel;

Fig 11: shows GC-SCD profiles of Clay treated marked kerosene, lvol% Clay treated marked kerosene in MS, and 1 % marked kerosene in MS; Fig 12: shows GC-SCD profiles of Clay treated marked kerosene, lvol% Clay treated marked kerosene in Diesel, and lvol% marked kerosene in Diesel;

Fig 13: shows GC-SCD profiles of HN03 treated marked kerosene, lvol% HN03 treated marked kerosene in Diesel, and lvoi% marked kerosene in Diesel:

Fig 14: shows GC-SCD profiles of H₂S0₄ treated marked kerosene, lvol% H₂S0₄ treated marked kerosene in Diesel, and lvoi% marked kerosene in Diesel:

Fig 15: shows GC-SCD profiles of KOH treated marked kerosene, lvol% OH treated marked kerosene in Diesel, and lvol% marked kerosene in Diesel.

DETAILED DESCRIPTION OF THE IN VENTION

The present invention discloses a method to detect adulteration of gasoline and diesel, with an adulterant, preferably, kerosene at a concentration ranging from 0.5voi% and above. The disclosed method includes mixing of known concentration of marker in kerosene, the said marker is an organo sulfur molecule or molecules preferably selected from a group comprising of diaikyl or diaryl or aikyl-aryl sulphide; or dialkyl or diary! or alkyl-aryl disulphide and more preferably from the group of dimethyl sulfide, dimethyl disulfide, diethyl sulfide, diethyl disulphide, diisopropyl disulphide, di-tert-butyl disulphide, dibenzyl sulphide, dibenzyl disulphide, thioanisole, thiophene, tetrahydrothiophene, substituted thiophenes, benzothiophene, substituted benzothiophenes, polysulphides or mixture thereof and then determining the concentration of marker in kerosene adulterated gasoline and diesel fuels employing gas chromatography with or without mass spectroscopy. The gas chromatography preferably operates with capillary column using the principle of sulfur chemi!uminescence detector (SCD), biolumineseence detector, flame photometric detector, pulsed flame photometric detector or lead acetate based detectors.

The disclosed invention provides a relatively simple process to detect fuel adulteration by determining the concentration of marker in adulterated gasoline and diesel fuels. Marking of fuel with disclosed organo sulfur molecule augurs well for its extensive use in detection of fuel adulteration as alternative to the existing chemical marker systems. Moreover, the method offers many advantages over the other chemical markers such as low cost, easy availability in petroleum refineries, easily miscible in hydrocarbon fuel, chemically stable in hydrocarbon, relatively chemically inert, less toxicity, ease of handling, difficult to remove from fuel, non- reactive with other fuel additives and easy detection by instrumental methods. In addition, this method provides accurate quantitative concentration of adulterant in gasoline and diesel fuels.

In the present invention, known concentration of marker is pre doped with neat kerosene fuel, which is subsequently mixed with gasoline and diesel fuels in different concentrations in order to make kerosene-gasoline and kerosene-diesel fuel composite. In the said method, kerosene content in motor spirit, aviation turbine fuel or diesel is in the range of 0.5vol% and above. The disclosed invention primarily involves determining the concentration of the extrinsic sulfur molecular marker (organo sulfur marker/organo sulfur compound), preferably for low concentrations of kerosene content in gasoline and diesel fuels by gas chromatography with or without mass spectroscopy. The gas chromatography detector is preferably based on the principle of sulfur chemiluminescence, photo-ionization, flame photometry or pulse flame photometry. The suggested technique is unique for analyzing the sulfur components, so that pool of hydrocarbon molecule interference can be avoided. The present invention is disclosed by ascertaining the concentration of non-fluorescent and low polar based chemical marker, preferably marker bearing the sulfur entity in kerosene adulterated gasoline and diesel fuels.

Gas chromatography with specific detector has been preferred for characterization and detailed analysis of sulfur compounds in petroleum fractions, more preferably in gasoline, kerosene and diesel fuels. There are some specific detectors selected from the group of flame photometric detector (FPD), pulsed flame photometric detector (PFPD), atomic emission detector (AED) or sulfur chemiluminescence detector (SCD). Of these, SCD, PFPD are widely used for analysis of sulfur compounds in petroleum samples because of its linearity, equimolar response to all kind of sulfur molecules, as well as its excellent sensitivity and selectivity as hydrocarbon interference is negligible. The GC-SCD technique is capable of separating the mercaptans, aliphatic sulfides, cyclic sulfides and thiophenic compounds based on their structural organizations.

In a first embodiment, a known concentration of chemically characteristic molecule, preferably, molecule bearings the sulfur entity chosen from the group of compounds dimethyl sulfide, dimethyl disulphide, diethyl sulfide, diethyl disulphide, diisopropyl disulphide, di-tert-butyl disulphide, dibenzyl sulphide, dibenzyl disulphide, thioanisole, thiophene, tetrahydro thiophene, benzothiophene or mixture thereof is doped or pre marked with kerosene fuel at the dispensing terminal. Hereafter the organo sulfur marker doped kerosene is referred as S-kerosene or marked kerosene. Further the S-kerosene preferably at a concentration of 1 vol % and 3 vol% or higher is mixed with gasoline and diesel. The resultant fuel blend is homogenized properly. The said process further involves the tracking and determining the marker in neat S-kerosene and gasoline and diesel fuels adulterated with S-kerosene employing the gas chromatography with or without mass spectroscopy. The gas chromatography preferably operates with capillar}' column embedded with Sulfur Chemiluminescence Detector (SCD), flame photometric detector or pulsed flame photometric detector (PFPD). A known volume of neat S-kerosene and adulterated gasoline and diesel fuels are injected into the GC equipped with SCD. The GC-SCD profiles (Fig 1 and 2) reveal the molecular distribution of different sulfur compounds in the samples. The GC- SCD profiles showed various signals and each signal is attributed to unique sulfur molecule existing in the hydrocarbon fuel, which are eluted in accordance with increase of molecular weight and polarity and structural organization. In addition, a well-defined peak pertinent to extrinsic organo sulfur molecule marker was noticed typically at the retention time of 2.8 min, which is distinctly resolved from the neighborhood sulfur compounds originally present in kerosene, gasoline and diesel.

The adulteration can be estimated quantitatively by integrating the area under the peak pertinent to the extrinsic sulfur molecule in S-kerosene adulterated gasoline and diesel fuel relative to the same in neat S-kerosene. The method provides the advantage of being reliable, amicable and requires very little quantity of organo sulfur molecular marker.

Following examples further illustrate the present invention without limiting the scope of the invention.

Example 1: 1. 100 ppm of dimethyl disulphide compound was doped into the kerosene fuel by vol/vol% and homogenized properly. The resultant marked kerosene was characterized by gas chromatography working with principle of sulfur chemiluminescence detector. The resulted GC profile (Fig 3) has shown a well-defined characteristic peak at retention time of 2.85 min, corresponds to dimethyl disulphide. Furthermore, the dimethyl disulphide resolved from the other peaks which are pertinent to sulfur compounds invariably present in kerosene fuel.

2. 1 vol% of S-kerosene was mixed with 99 ml of gasoline and resultant fuel composite was homogenized. The resulted fuel blend was characterized by GC-SCD, The GC profile (Fig 3) showed the presence of well-defined peak pertinent to dimethyl disulphide marker at retention time of 2.85 rnin. Further, the peak integration analysis reveals that, relative area under organo sulphur marker in kerosene mixed gasoline fuel to the same in neat S-kerosene implies that gasoline fuel was adulterated with lvol% of kerosene.

3. I vol% of S-kerosene was mixed with 99 ml of diesel and resultant fuel composite was homogenized. The resultant fuel blend was characterized by GC-SCD. The GC profile (Fig 4) showed the presence of well-defined peak pertinent to dimethyl disulphide at retention time of 2.85 min. Further, the peak integration analysis reveals that, relative area under dimethyl disulphide in kerosene mixed gasoline fuel to the same in neat S-kerosene implies that gasoline fuel was adulterated with lvol% of kerosene.

Example 2:

1. Kerosene fuel was taken up as adulterant for gasoline and diesel fuel. The sulphur content of kerosene fuel was determined by X-ray Fluorescence spectroscopy (XRF) and was measured as 1200 ppm. Further, 100 ppm of an dimethyl disulphide (Marker 1) was doped into the kerosene fuel by voi/voi% and homogenized properly. The resultant marked kerosene was characterized by gas chromatography working with principle of sulfur chemiluminescence detector. The resulted GC profile (Fig 1) has shown a well- defined characteristic peak at retention time of 2,85 min, which is pertinent to extrinsic dimethyl disulphide. Furthermore, peak pertinent to said dimethyl disulphide is well resolved from the other peaks pertinent to sulfur compounds which are invariably present in kerosene fuel.

2, 0.5vol%, lvol% 3vol% and 5 vol% of marker- 1 doped kerosene was mixed with 99.5, 99, 97, 95 ml of gasoline fuel (75 ppm of Sulphur by XRF) and resultant fuel composite was homogenized. The resulted fuel blend was characterized by GC-SCD. The GC profile (Fig 1) showed the presence of well-defined peak pertinent to dimethyl disulphide at retention time of 2.85 min. Further, quantity of adulterant (Kerosene) in gasoline fuel is estimated by relative peak integration of organo sulphur marker in kerosene mixed gasoline fuel to the same in neat marker- 1 doped kerosene implies the composition of adulterant (kerosene) present in gasoline fuel.

3. 0.5 vol%, lvol%, 3vol%, of dimethyl disulphide doped kerosene was mixed with 99.5, 99, 97, ml of diesel fuel (65ppm of sulphur by XRF) and resultant fuel composite was homogenized. The resultant fuel blend was characterized by GC-SCD. The GC profile (Fig 2) showed the presence of well-defined peak pertinent to dimethyl disulphide at retention time of 2.85 min. Further, quantity of adulterant (Kerosene) in diesel fuel is estimated by relative peak integration of organo sulphur marker in kerosene mixed diesel fuel to the same in neat marker- 1 doped kerosene implies the composition of adulterant (kerosene) present in diesel fuel.

4. lvol%, 3vol% of marker- 1 doped kerosene was mixed with 99, 97 ml of gasoline fuel (15 ppm of sulphur by XRF) and fuel composite was homogenized. The resultant fuel blend was characterized by GC-SCD. The GC profile (Fig 3) showed the presence of well-defined peak pertinent to dimethyl disulphide at retention time of 2.85 min. Further, quantity of adulterant (Kerosene) in gasoline fuel is estimated by relative peak integration of organo sulphur marker in kerosene mixed gasoline fuel to the same in neat marker- 1 doped kerosene implies the composition of adulterant (kerosene) present in gasoline fuel.

5. 0.5 vol%, lvol%, 3vol% and 5vol%, of dimethyl disulphide doped kerosene was mixed with 99.5, 99, 97 and 95ml of diesel fuel (25 ppm of sulphur by XRF) and resultant fuel composite was homogenized. The resulted fuel blend was characterized by GC-SCD. The GC profile (Fig 4) showed the presence of well-defined peak pertinent to dimethyl disulphide at retention time of 2.85 min. Further, quantity of adulterant (Kerosene) in diesel fuel is estimated by relative peak integration of organo sulphur marker in kerosene mixed diesel fuel to the same in neat marker- i doped kerosene implies the composition of adulterant (kerosene) present in diesel fuel. The following examples illustrate the use of additional marker molecules from the group of markers of the present invention for detection of kerosene adulterant in gasoline and diesel fuels:

6. 100 ppm of dibutyl sulphide molecule was doped in kerosene fuel (vol/vol %) and resultant marked kerosene of lvol% was mixed with 99 ml of gasoline fuel (75 ppm of

Sulphur by XRF) and diesel fuel (65 ppm of Sulphur). The resultant kerosene mixed gasoline and diesel fuel blend was characterized by GC-SCD. The GC profile (Fig 5) showed the presence of well-defined peak pertinent to dibutyl sulphide at retention time of 4.1 min. Further, quantity of adulterant (Kerosene) in gasoline & diesel fuel is estimated by relative peak integration of organo sulphur marker in kerosene mixed diesel fuel to the same in neat marker-2 doped kerosene implies the composition of adulterant (kerosene) present in gasoline and diesel fuel.

7. 100 ppm of phenyl methyl sulphide molecule was doped in kerosene fuel (voi/voi%) and resulted marked kerosene of lvol% was mixed with 99 ml of gasoline fuel (75 ppm of Sulphur by XRF) and diesel fuel (65 ppm of Sulphur) respectively. The resultant kerosene mixed gasoline and diesel fuel blend further characterized by GC-SCD. The GC profile (Fig 6) showed the presence of well-defined peak pertinent to phenyl methyl sulphide at retention time of 4.1 min. Further, quantity of adulterant (Kerosene) in gasoline & diesel fuel is estimated by relative peak integration of organo sulphur marker in kerosene mixed diesel fuel to the same in neat marker- 3 doped kerosene implies the composition of adulterant (kerosene) present in gasoline and diesel fuel.

8. 100 ppm of di -tertiary butyl di sulphide was doped in kerosene fuel (vol/vol%) and resultant marked kerosene of lvol% was mixed with 99 ml of gasoline fuel (75 ppm of

Sulphur by XRF) and diesel fuel (65 ppm of Sulphur). The resultant kerosene mixed gasoline arid diesel fuel blend was characterized by GC-SCD. The GC profile (Fig 7) showed the presence of well -defined peak pertinent to organo sulfur marker at retention time of 4.5 min. Further, quantity of adulterant (Kerosene) in gasoline & diesel fuel was estimated by relative peak integration of organo sulphur marker in kerosene mixed diesel fuel to the same in neat marker-4 doped kerosene implies the composition of adulterant (kerosene) present in gasoline and diesel fuel.

9, 100 ppm of Diphenyl disulphide was doped in kerosene fuel (vol/vol%) and resultant marked kerosene of lvol% was mixed with 99 ml of gasoline fuel (75 ppm of Sulphur by XRF) arid diesel fuel (65 ppm of Sulphur). The resultant kerosene mixed gasoline and diesel fuel blend was characterized by GC-SCD. The GC profile (Fig 8) showed the presence of well-defined peak pertinent to organo sulfur marker at retention time of 16.2 min. Further, quantity of adulterant (Kerosene) in gasoline & diesel fuel is estimated by relative peak integration of organo sulphur marker in kerosene mixed diesel fuel to the same in neat marker-5 doped kerosene implies the composition of adulterant (kerosene) present in gasoline and diesel fuel.

Example 3:

The disclosed markers of the present invention are also tampering proof, i.e., despite treatment of the adulterated fuels or kerosene with various tampering methods, such as, subjecting the marked kerosene to various chemical reagents such as HC1, H₂S0₄, HN0₃, and KOH, the markers of the present invention can be detected. Detection of kerosene in gasoline and diesel fuels was found possible by tracking extrinsic markers even after laundering. On the other hand, the surface adsorption tendency of marker also assessed over notable adsorbents such as activated carbon, clay and found that the markers are detected even after adsorption. Therefore detection of laundered kerosene adulteration in gasoline and diesel fuel is possible by tracking extrinsic markers of the present invention even after laundering (Fig 9-15).

1. Each 5 g of oven dried activated charcoal and clay powder adsorbents taken in two separate beakers and 100 mL of marked kerosene was added and kept under stirring for 1 h. The resultant activated charcoal and clay treated marked kerosene was further analysed by GC-SCD technique. A close examination of the GC profile reveals that, no significant iaunderability of organo sulphur marker molecule was observed. Subsequent!}', activated charcoal and clay treated marked kerosene has been used as adulterant for gasoline and diesel. Accordingly, lvol% of treated marked kerosene was mixed with 99 vol% of gasoline and diesel fuel and subsequently analysed by GC-SCD technique. The GC-SCD profile of the above said fuel mixture reveal that well resolved marker peak is noticed as like in untreated marked kerosene samples (Fig 9-12).

2. Each 100 mL of marked kerosene was mixed with 100 mL of 1M of HN0₃, H₂S0₄, and KOH in separate beakers. The resultant fuel composite kept under stirring for 1 hr, Further aqueous and organic layers were allowed to separate and marked kerosene was subsequently washed twice with water in order to remove the trace of acid or base impurities followed by drying over MgS0₄. The resultant acid and base treated marked kerosene were further characterized by GC-SCD in order to know the concentration of remaining organo sulphur marker. A close examination of the GC profile reveals that, no significant launderability of organo sulphur marker molecule was observed.

Subsequently, acid and base treated marked kerosene has been used as adulterant for diesel fuel. Accordingly, lvof% of acid and base treated marked kerosene was mixed with 99 vol% of diesel fuel and subsequently analyzed by GC-SCD technique. The GC- SCD profile of the above said fuel mixture reveal that well resolved marker peak is noticed as like in untreated marked kerosene samples (Fig 13-15).

Claims

We Claim:

1. A method of detecting kerosene adulteration in a fuel, the method comprising detecting the presence of an organo sulphur marker in the fuel, wherein the kerosene is pre-marked with said organo sulphur marker, and wherein the fuel is adulterated with said pre-marked kerosene in an amount of 0.5 vol% or more.

2. The method as claimed in claim 1 wherein the fuel is gasoline, aviation turbine fuel or diesel.

3. The method as claimed in claim 1 , wherein the said organo sulfur marker is a molecule or molecules bearing a C-S bond, S-S bond or both.

4. The method as claimed in claim 3, wherein the organo sulfur marker is selected from a group comprising of dialkyl/diaryl/aikyl-aryl sulphide and dialkyl/diaryl/alkyl-aryl disulphide compounds, which includes dimethyl sulfide, dimethyl disulfide, diethyl sulfide, diethyl disulphide, diisopropyl disulphide, di-tert-butyl disulphide, dibenzyl sulphide, dibenzyl disulphide, thioanisole, thiophene, tetrahydrothiophene, methyl substituted thiophenes, benzothiophene, mono, di and tri methyl substituted benzothiophenes, polysulphides or mixtures thereof.

5. The method as claimed in claim 1 , wherein the organo sulfur molecule is detected by gas chromatography.

6. The method as claimed in claim 5, wherein the gas chromatography is performed by sulfur chemiluminescence detector (SCD), bioluminescence detector, flame photometric detector, pulsed flame photometric detector or lead acetate based detector.

7. The method as claimed in claim 5, wherein the gas chromatography is performed with or without mass spectroscopy.

8. A method of marking kerosene with an organo sulphur marker, the method comprising adding an organo sulphur compound to kerosene in an amount of 10 ppm to 100 ppm.

9. The method as claimed in claim 8, wherein the organo sulfur marker is a molecule or molecules bearing a C-S bond, S-S bond or both.

10. The method as claimed in claim 9, wherein the organo sulfur marker is selected from a group comprising of dialkyl/diaryl/alkyl-aryl sulphide and dialkyl/diaryl/alkyl-aryl disulphide compounds, which includes dimethyl sulfide, dimethyl disulfide, diethyl sulfide, diethyl disulphide, diisopropyl disulphide, di-tert-butyl disulphide, dibenzyl sulphide, dibenzyl disulphide, thioanisole, thiophene, tetrahydrothiophene, methyl substituted thiophenes, benzothiophene, mono, di and tri methyl substituted benzothiophenes, polysulphides or mixtures thereof.

1 1. A marked kerosene product, wherein the kerosene is marked with an organo sulphur marker in a concentration of 10 ppm to 100 ppm.

12. The product as claimed in claim 1 1 , wherein the organo sulfur marker is a molecule or molecules bearing a C-S bond, S-S bond or both.

13. The product as claimed in claim 12, wherein the organo sulfur marker is selected from a group comprising of dialkyl/diaryl/alkyl-aryl sulphide and dialkyl/diaryl/alkyl-aryl disulphide compounds, which includes dimethyl sulfide, dimethyl disulfide, diethyl sulfide, diethyl disulphide, diisopropyl disulphide, di-tert-butyl disulphide, dibenzyl sulphide, dibenzyl disulphide, thioanisole, thiophene, tetrahydrothiophene, methyl substituted thiophenes, benzothiophene, mono, di and tri methyl substituted benzothiophenes, polysulphides or mixtures thereof.

14. A marker for detection of an adulterant in a fuel, the marker being selected from an organo sulfur compound containing C-S bond, S-S bond or both, and wherein the marker is added in an amount of 10 ppm to 1 00 ppm in the said adulterant.

15. The marker as claimed in claim 14, wherein the organo sulfur compound is selected from a group comprising of dialkyl/diaryl/alkyl-aryl sulphide and dialkyl/diaryl/alkyl-aryl disulphide compounds, which includes dimethyl sulfide, dimethyl disulfide, diethyl sulfide, diethyl disulphide, diisopropyl disulphide, di-tert-butyl disulphide, dibenzyl sulphide, dibenzyl disulphide, thioanisole, thiophene, tetrahydrothiophene, methyl substituted thiophenes, benzothiophene, mono, di and tri methyl substituted benzothiophenes, polysulphides or mixtures thereof.