Comprehensive two-dimensional gas chromatography with time-of-flight mass spectrometric detection for the determination of anabolic steroids and related compounds in nutritional supplements

A simple and effective analytical method for the determination of anabolic steroids and related compounds in nutritional supplements is reported. Target compounds are extracted with ethyl acetate, crude extract is purified using dispersive solid-phase extraction (SPE) with primary secondary amine (PSA) as sorbent, and finally they are identified and quantified as underivatized compounds using two-dimensional gas chromatography with time-of-flight mass spectrometric detection (GCxGC-TOF MS). This method was validated for 25 steroids in two types of commercially available solid nutritional supplements: protein concentrate and creatine monohydrate. Repeatability expressed as the relative standard deviation of analyte concentration ranged from 4.1 to 20.5%. Recoveries between 70.0 and 122.6% were obtained for the target compounds except for oxymetholone in protein concentrate where the recovery was low as a result of strong interactions with PSA. Excellent linearity was obtained for six-point calibration with regression coefficients of 0.997-1.000 for all compounds. The limits of quantification ranged from 0.007 to 0.114 mg kg(-1). For a monitoring programme of 48 samples of nutritional supplements, three were positive. Nandrolone, testosterone, dehydroepiandrosterone (DHEA), 5alpha-androstan-3,17-dione, 19-norandrostendione and progesterone were found in positive samples at concentrations between 0.022 and 0.398 mg kg(-1).

A solution for isomerization of pyrethroid insecticides in gas chromatography

Isomerization of pyrethroid insecticides was observed during extraction and gas chromatography (GC) analysis. An improvement in sensitivity was noted for pyrethroids in sediment extracts in comparison to pure solvent. Stability of pyrethroids using different solvents and analyte additives were investigated, and GC injection conditions were optimized. Polar solvents enhanced pyrethroid isomerization, while hexane was the best choice as an analytical solvent. Acetic acid was used successfully as an isomer-stabilizing agent for GC analysis of pyrethroids. Acidified (0.1% acetic acid) hexane prevented pyrethroid isomerization, increased peak intensity up to 1.9 times, and calibration curve linearity (relative standard deviation for response factors) 0.8-12.5 times compared to hexane alone.

Matrix-induced response enhancement in pesticide residue analysis by gas chromatography

The sample matrix can cause an enhancement in the observed chromatographic response for pesticide residues in a matrix extract compared with the same concentration in a matrix-free solution. The matrix increases the transfer of pesticides from hot vaporizing injectors by reducing the thermal stress for labile compounds and by masking active sites in the injector responsible for the adsorption or decomposition of polar pesticides. The use of different injector types and matrix simplification procedures can reduce matrix-induced enhancement but do not eliminate it. The most effective strategy is to use matrix-matched calibration standards or analyte protectants which equalize the response enhancement for calibration standards and sample extracts. From a practical point of view it is important that the method used to correct for matrix-induced enhancement is compatible with low system maintenance. The different approaches for correcting matrix-induced enhancement for calibration in pesticide residue analysis are discussed and compared in this review.

Use of SPE-GC/EIMS for residue analysis in wine elaborated from musts spiked with formulations of chlorpyriphos-methyl, methiocarb, dicofol, and cyproconazol

The likely presence in wine of residues of the active ingredient and its degradation products, besides the byproducts and excipients of the commercial formulation, has been investigated for four pesticides. Formulations containing chlorpyriphos-methyl, methiocarb, dicofol, and cyproconazol were added to must, which was subjected to a usual vinification. The wines elaborated from must spiked with the formulation of chlorpyriphos-methyl contained two pyridinol compounds in addition to excipients such as alkylbenzenes, naphthalene, and methylnaphthalenes. Methiocarb was hydrolyzed to yield the corresponding phenol, and various unidentified compounds related to cyproconazol were observed in wine. The residues of the dicofol-containing formulation resulted to be dechlorination products; impurities from its commercial formulation were also detected in must and wine extracts. White wines contained higher amounts of residues than red wines. The residues were detected after an SPE followed by GC/EIMS in the scan mode. The concentrations of the active ingredients were determined by a matrix-matched calibration to avoid quantitative errors arising from the matrix.

Effect of residues remaining in the injection liner of a gas chromatograph on the quantification of polycyclic aromatic hydrocarbons by isotope dilution mass spectrometry using deuterium-labeled internal standards

We have investigated the differences in response ratios of native polycyclic aromatic hydrocarbons (native PAHs)/13C-labeled PAHs (13C-PAHs) and of native PAHs/deuterium-labeled PAHs (PAHs-d) in a calibration solution containing at trace concentrations (< 1 microg mL(-1)) by gas chromatography-mass spectrometry. Only the ratios of native PAHs/PAHs-d decreased significantly (p < 0.05) accompanied with increase of residue amounts originated from immediately before injected solution. Since the analytical results using PAHs-d as internal standards were significantly lower than those using 13C-PAHs whatever solutions were injected immediately before (p < 0.05, 1.9-13.2%), 13C-PAHs gave more accurate results.

Comparison of an acetonitrile extraction/partitioning and “dispersive solid-phase extraction” method with classical multi-residue methods for the extraction of herbicide residues in barley samples

An acetonitrile/partitioning extraction and "dispersive solid-phase extraction (SPE)" method that provides high quality results with a minimum number of steps and a low solvent and glassware consumption was published in 2003. This method, suitable for the analysis of multiple classes of pesticide residues in foods, has been given an acronymic name, QuEChERS, that reflects its major advantages (quick, easy, cheap, effective, rugged, safe). In this work, QuEChERS method, which was originally created for vegetable samples with a high amount of water, was modified to optimise the extraction of a wide range of herbicides in barley. Then, it was compared with known conventional multi-residue extraction procedures such as the Luke method, which was simplified and shortened by eliminating the Florisil clean-up (mini Luke) and the ethyl acetate extraction, which involves a subsequent clean-up by gel permeation chromatography (GPC) and which is the official extraction method used by some of European authorities. Finally, a simple acetone extraction was carried out to check the differences with the other three methods. Extracts were analysed by gas chromatography-time-of-flight mass spectrometry (GC-TOF/MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mini Luke was significantly more effective for the extraction of non-polar and medium-polar compounds, but the best recoveries for polar compounds were achieved by QuEChERS and ethyl acetate methods. QuEChERS was the only method that provided an overall recovery value of 60-70% for non-, medium- and polar compounds, with some exceptions due to co-eluted matrix interferences. Clean-up by dispersive SPE was effective and did not differ so much with ethyl acetate extracts considering that QuEChERS clean-up step is much easier and less time-consuming. As a conclusion, it resulted to be the most universal extraction method by providing a well-defined phase separation without dilution and achieving acceptable recoveries in average including the extraction of the always difficult acidic herbicides. However, recoveries were not as good as required for validation purposes suggesting that residues are prone to strong matrix interactions in dry samples as barley and further method adaptation incrementing solvent strength, extraction time or more acidic or basic conditions is needed in order to achieve a complete extraction.

Multiresidue determination of pesticides in malt beverages by capillary gas chromatography with mass spectrometry and selected ion monitoring

A method was developed to determine pesticides in malt beverages using solid phase extraction on a polymeric cartridge and sample cleanup with a MgSO4-topped aminopropyl cartridge, followed by capillary gas chromatography with electron impact mass spectrometry in the selected ion monitoring mode [GC-MS(SIM)]. Three GC injections were required to analyze and identify organophosphate, organohalogen, and organonitrogen pesticides. The pesticides were identified by the retention times of peaks of the target ion and qualifier-to-target ion ratios. GC detection limits for most of the pesticides were 5-10 ng/mL, and linearity was determined from 50 to 5000 ng/mL. Fortification studies were performed at 10 ng/mL for three malt beverages that differ in properties such as alcohol content, solids, and appearance. The recoveries from the three malt beverages were greater than 70% for 85 of the 142 pesticides (including isomers) studied. The data showed that the different malt beverage matrixes had no significant effect on the recoveries. This method was then applied to the screening and analysis of malt beverages for pesticides, resulting in the detection of the insectide carbaryl and the fungicide dimethomorph in real samples. The study indicates that pesticide levels in malt beverages are significantly lower than the tolerance levels set by the United States Environmental Protection Agency for malt beverage starting ingredients. The use of the extraction/cleanup procedure and analysis by GC-MS(SIM) proved effective in screening malt beverages for a wide variety of pesticides.

Determination of polar organophosphorus pesticides in vegetables and fruits using liquid chromatography with tandem mass spectrometry: selection of extraction solvent

A method based on liquid chromatography (LC)-mass spectrometry (MS)/MS was developed for sensitive determination of a number of less gas chromatography (GC)-amenable organophosphorus pesticides (OPs; acephate, methamidophos, monocrotophos, omethoate, oxydemeton-methyl and vamidothion) in cabbage and grapes. For extraction, several solvents were evaluated with respect to the possibility of direct injection, matrix-induced suppression or enhancement of response, and extraction efficiency. Overall, ethyl acetate was the most favourable solvent for extraction, although a solvent switch was required. For some pesticide/matrix combinations, reconstitution of the residue after evaporation required special attention. Extracts were analysed on a C18 column with polar endcapping. The pesticides were ionised using atmospheric pressure chemical ionisation on a tandem mass spectrometer in multiple reaction monitoring mode. The final method is straightforward and involves extraction with ethyl acetate and a solvent switch to 0.1% acetic acid/water without further cleanup. The method was validated at the 0.01 and 0.5 mg/kg level, for both cabbage and grapes. Recoveries were between 80 and 101% with R.S.D. < 11% (n = 5). The limit of quantification was 0.01 mg/kg and limits of detection were between 0.001 and 0.004 mg/kg.

Evaluation of analyte protectants to improve gas chromatographic analysis of pesticides

A common problem in gas chromatography (GC) applications is the analyte losses and/or peak tailing due to undesired interactions with active sites in the inlet and column. Analytes that give poor peak shapes or degrade have higher detection limits, are more difficult to identify and integrate, and are more prone to interferences than stable analytes that give narrow peaks. For susceptible analytes, significant peak quality improvements are obtained when matrix components are present because they fill active sites, thus reducing analyte interactions. This phenomenon is called "matrix-induced chromatographic response enhancement." Several approaches have been proposed to minimize peak distortion phenomena and compensate for matrix-induced effects, which is especially important for accurate quantitation, but each approach has serious limitations for routine multi-pesticide analysis. In this study, we demonstrate the feasibility of using "analyte protectants" to provide a more convenient and effective solution to the problem than other approaches developed thus far. The protecting agents are added to extracts and matrix-free standards alike to provide the chromatographic enhancement effect even for the most susceptible analytes in a very dirty GC system. In this study, we evaluated 93 different compounds to find the most suitable ones for improving chromatographic quality of the signal. Because hydrogen bonding has been shown to be an important factor in analyte interactions with active sites, we mainly focused on additives with strong hydrogen bonding capabilities. Dramatic peak enhancements were achieved using compounds containing multiple hydroxy groups, such as sugars and sugar derivatives, and gulonolactone appears to be the most effective protecting agent for the most pesticides that we tested. The benefits of using analyte protectants versus alternative procedures for overcoming matrix-induced effects in quantitation include: (a) simpler procedure; (b) easier integration of peaks; (c) lower detection limits; (d) better quantitation; (e) less maintenance of the GC inlet; and (e) lower cost. However, long-term influences on the performance of the chromatographic system have yet to be established.

Matrix effects in (ultra)trace analysis of pesticide residues in food and biotic matrices

If one has to determine multiple residues of modem pesticides and/or other groups of (semi)polar and/or thermally unstable contaminants with a wide range of physico-chemical properties within a single analytical run, it can be complicated to obtain low limits of quantitation (LOQ), good precision as well as relevant trueness of results for all the target analytes. Matrix components, which are unavoidably present in analyzed samples (even after the thorough clean-up step), may be responsible for miscellaneous adverse affects impairing different stages of the GC and/or LC determinative step. In this review, the nature of various types of matrix effects are discussed together with suggestions for prevention, reduction and/or compensation of their occurrence when determining troublesome analytes in foods and other complex biotic matrices.

Rapid multi-residue method for the determination of azinphos methyl, bromopropylate, chlorpyrifos, dimethoate, parathion methyl and phosalone in apricots and peaches by using negative chemical ionization ion trap technology

A rapid, selective and sensitive multi-residue method for the determination of six common pesticides in stone fruit samples is described. The proposed method involves the extraction of the pesticides with the use of acetone solvent followed by liquid-liquid partition with a mixture of dichloromethane and light petroleum (40-60 degrees C) and subsequent determination by a gas chromatographic-mass spectrometry system using ion trap technology in negative ion chemical ionization mode. The average percent recoveries of bromopropylate and phosalone in the concentration range 0.2-2.0 mg/kg were 97.3 +/- 6.7 to 120 +/- 1.0%, while the recoveries of chlorpyrifos and parathion methyl examined in the concentration range 0.02-0.2 mg/kg were 95.5 +/- 7.5 to 145 +/- 3.6%, the recoveries of azinphos methyl in the range 0.05-0.5 mg/kg were 74.8 +/- 29.6 to 96.5 +/- 13% and those of dimethoate in the range 0.1-1.0 mg/kg were 73.1 +/- 5.7 to 92.8 +/- 2.8% for n = 3 for all the above pesticides. The high mean recovery (145%) for chlorpyrifos is attributed to a matrix enhancement effect. The limits of quantitation in apricots were 0.01 mg/kg for chlorpyrifos, 0.02 mg/kg for dimethoate and parathion methyl, 0.05 mg/kg for azinphos methyl and phosalone and 0.1 mg/kg for bromopropylate. The usefulness of tandem mass spectrometry for confirmation purposes was also examined. The method was applied successfully to the determination of the target pesticides in 32 samples of stone fruits (apricots and peaches).

Development of a gas chromatography-mass spectrometry method for the determination of household insecticides in indoor air

This work presents a GC-MS method for the determination of 17 household insecticides and acaricides in indoor air. Air samples were collected with a sampling train which consisted of a glass fibre filter and two polyurethane foam plugs, followed by a high-volume air pump. Filters and plugs were analysed separately. The overall recoveries ranged from 85 to 109% (4-11% RSD). Minimum method detection limits between 0.1 and 5 ng/m3 were determined.

Performance of programmed temperature vaporizer, pulsed splitless and on-column injection techniques in analysis of pesticide residues in plant matrices

A programmed temperature vaporizer (PTV) injection technique has been recently implemented in our laboratory. In present paper its performance is compared with other GC injection techniques commonly used in trace analysis of organic contaminants. Twenty-six pesticides representing different chemical classes were selected for the study. This group comprised compounds typically subjected to discrimination in the injection port of the gas chromatograph, e.g., polar organophosphorus pesticides and thermolabile carbamates. In the first set of experiments standards in pure solvent were injected into GC systems employing different types of injection, i.e., (i) on-column, (ii) pulsed splitless, (iii) PTV solvent split, (iv) PTV splitless, and the responses of analytes were compared. Discrimination of troublesome compounds was significantly decreased with the application of PTV solvent split injection. In the second set of experiments repetitive injections of purified wheat samples were performed, with aims to evaluate the long-term stability of responses, as well as matrix effects in different stages of system contamination for each injection technique. The tolerance of the GC system to co-injected matrix components was increased in the order: on-column<pulsed splitless<PTV solvent split technique. As regards matrix effects, these were suppressed considerably with the PTV solvent split technique in comparison with pulsed splitless injection. With the latter technique after 66 injections of wheat samples relative responses (apparent recovery) reached as much as 450% for some compounds, while with the application of PTV matrix effects did not exceed 200% under the same conditions.

Analysis of pesticide residues in eggs by direct sample introduction/gas chromatography/tandem mass spectrometry

Direct sample introduction (DSI) or "dirty sample injection" is a rapid, rugged, and inexpensive approach to large volume injection in gas chromatography (GC) for semivolatile analytes such as pesticides. DSI of complex samples such as eggs requires a very selective detection technique, such as tandem mass spectrometry (MS-MS), to determine the analytes among the many semivolatile matrix components that also appear. In DSI, the nonvolatile matrix components that normally would contaminate the GC system in traditional injection methods remain in a disposable microvial, which is removed after every injection. For example, 3 microg of nonvolatile residue typically remained in the microvial after an injection of egg extract using the DSI method. This analytical procedure involves the following: (i) weighing 10 g of egg in a centrifuge tube and adding 2 g of NaCl and 19.3 mL of acetonitrile (MeCN); (ii) blending for 1 min using a probe blender; (iii) centrifuging for 10 min; and (iv) analyzing 10 microL (5 mg of egg equivalent) of the extract using DSI/GC/MS-MS. No sample cleanup or solvent evaporation steps were required to achieve quantitative and confirmatory results with <10 ng/g detection limits for 25 of 43 tested pesticides from several chemical classes. The remaining pesticides gave higher detection limits due to poor fragmentation characteristics in electron impact ionization and/or degradation. Analysis of eggs incurred with chlorpyrifos-methyl showed a similar trend in the results as a more traditional approach.

Optimization and evaluation of low-pressure gas chromatography-mass spectrometry for the fast analysis of multiple pesticide residues in a food commodity

A fast method of analysis for 20 representative pesticides was developed using low-pressure gas chromatography-mass spectrometry (LP-GC-MS). No special techniques for injection or detection with a common quadrupole GC-MS instrument were required to use this approach. The LP-GC-MS approach used an analytical column of 10 m x 0.53 mm I.D., 1 microm film thickness coupled with a 3 m x 0.15 mm I.D. restriction capillary at the inlet end. Thus, the conditions at the injector were similar to conventional GC methods, but sub-atmospheric pressure conditions occurred throughout the analytical column (MS provided the vacuum source). Optimal LP-GC-MS conditions were determined which achieved the fastest separation with the highest signal/noise ratio in MS detection (selected ion monitoring mode). Due to faster flow-rate, thicker film, and low pressure in the analytical column, this distinctive approach provided several benefits in the analysis of the representative pesticides versus a conventional GC-MS method, which included: (i) threefold gain in the speed of chromatographic analysis; (ii) substantially increased injection volume capacity in toluene; (iii) heightened peaks with 2 s peak widths for normal MS operation; (iv) reduced thermal degradation of thermally labile analytes, such as carbamates; and (v) due to larger sample loadability lower detection limits for compounds not limited by matrix interferences. The optimized LP-GC-MS conditions were evaluated in ruggedness testing experiments involving repetitive analyses of the 20 diverse pesticides fortified in a representative food extract (carrot), and the results were compared with the conventional GC-MS approach. The matrix interferences for the quantitation ions were worse for a few pesticides (acephate, methiocarb, dimethoate, and thiabendazole) in LP-GC-MS, but similar or better results were achieved for the 16 other analytes, and sample throughput was more than doubled with the approach.

Determination of residues of endosulfan and five pyrethroid insecticides in virgin olive oil using gas chromatography with electron-capture detection

A simple, fast and economical method has been developed for the determination of endosulfan and five pyrethroid insecticides, cypermethrin, deltamethrin, fenvalerate, lambda-cyhalothrin and permethrin, in virgin olive oil. The method uses a Sep-Pak alumina-N column cleanup after a liquid-liquid extraction or low-temperature precipitation step, and gas chromatography (GC) with electron-capture detection. The matrix effect was assessed for the GC systems used. Recoveries were 71-91% with RSD values of 6-17%. The method was applied to 338 virgin olive oil samples for monitoring of residues of these pesticides. Cypermethrin and lambda-cyhalothrin were detected at the limit of quantification in one sample each, while 22% of samples contained endosulfan residues, mostly at very low levels ranging from 0.02 to 0.57 mg/kg.

Analysis of pesticide residues in wine by solid-phase extraction and gas chromatography with electron capture and nitrogen-phosphorus detection

A feasible and reproducible method for multiresidue analysis of several common pesticides, of different polarities, in wine samples is proposed. The method combines a solid-phase extraction on polymeric cartridges eluted with ethyl acetate and a gas chromatographic determination using electron capture and nitrogen-phosphorus detection. To avoid the matrix effect, previous washing of the cartridges with a mixture of water-2-propanol (90:10) and further clean-up of the extract on Florisil cartridges, together with a calibration using spiked extracts, are recommended.

Supercritical-fluid extraction of synthetic pyrethroids from wool

A stepwise approach was used to develop a supercritical fluid extraction (SFE) method for analysis of synthetic pyrethroids (SPs) on a wool matrix, commencing with a simple inert matrix to examine the solubility of the pyrethroids in the extraction fluid CO(2) and then extended to the real wool matrix. Chemometric approaches were used to determine the SFE optimum conditions. It was found that pyrethroids were readily extractable from an inert matrix over a wide range of pressure (170-350 atm) and at low temperature (<90 degrees C). Subambient hexane efficiently trapped the compounds from the depressurised fluid. Excessively high pressure and temperature resulted in poor trapping, isomerisation and possibly degradation of some components. With spiked wool samples method modifications focused on reducing the coextraction of grease, a bulk matrix component of raw wool. By using alumina (containing 8% moisture) and operating the extraction at 50 degrees C, 200 atm for 60 min, sufficiently clean extracts of pyrethroids suitable for gas chromatography-electron-capture detection analysis were obtained. The recoveries of all SPs were satisfactory (78-101%) over the range of 0.5-5 microg/g levels of these compounds. The precision of the entire analysis procedure was comparable to the conventional Soxhlet extraction method. Detection limits of some commonly used SPs for sheep treatment were also evaluated. Comparable results relative to those achieved by solvent extraction for incurred wool samples were obtained with a recovery of 81-85%. The results, however, suffered high uncertainties (R.S.D. approximately 19-24%) due to the small amount of wool sample taken in each extraction and the suspected inhomogeneity of the wool. Different persistences of cypermethrin isomers in wool were observed.

Does further clean-up reduce the matrix enhancement effect in gas chromatographic analysis of pesticide residues in food?

Sample extracts of apples, peas, green beans, oranges, raspberries, clementines, carrots, and wheat obtained using the Food and Drug Administration (acetone extraction) and Canadian Pest Management Regulatory Agency (acetonitrile extraction) multiresidue methods for pesticides were subjected to clean-up using different solid-phase extraction (SPE) cartridges in an attempt to reduce or eliminate the matrix enhancement effect. The matrix enhancement effect is related to the blocking of active sites on the injector liner by matrix components, thereby increasing signal in the presence of matrix versus standards in solvent in which the pesticides themselves interact with the active sites. Graphitized carbon black (GCB) was often used in combination with various anion-exchange SPE cartridges. The extracts were then spiked with organophosphorus insecticides. These process standards were then compared to standards in acetone of the same concentration using gas chromatography with flame photometric detection or ion trap mass spectrometric detection. Sample matrix enhancement varied from little to no effect for some pesticides (e.g. chlorpyrifos, malathion) to >200% in the case of certain susceptible pesticides. The GCB removed color components but showed little effect in reducing matrix enhancement by itself. The anion-exchange cartridges in combination with GCB or not, substantially reduced the matrix enhancement effect but did not eliminate it.

Trace analysis of pesticides by gas chromatography

The analysis of pesticides is relevant to both food quality and the environment. Many laboratories are occupied with the analysis of pesticides in food, water or soil. Capillary gas chromatography is the technique most widely used in pesticide analysis. In present laboratory practice it serves as a screening method for over 300 pesticides. In this review we describe the role of gas chromatography as an analytical tool in combination with currently used or recently developed sample preparation techniques.

Gas chromatography

This review of the fundamental developments in gas chromatography (GC) includes articles published from 1996 and 1997 and an occasional citation prior to 1996. The literature was reviewed principally using CA Selects for Gas Chromatography from Chemical Abstracts Service, and some significant articles from late 1997 may be missing from the review. In addition, the online SciSearch Database (Institute for Scientific Information) capability was used to abstract review articles or books. As with the prior recent reviews, emphasis has been given to the identification and discussion of selected developments, rather than a presentation of a comprehensive literature search, now available widely through computer-based resources. During the last two years, several themes emerged from a review of the literature. Multidimensional gas chromatography has undergone transformation encompassing a broad range of activity, including attempts to establish methods using chromatographic principles rather than a totally empirical approach. Another trend noted was a comparatively large effort in chromatographic theory through modeling efforts; these presumably became resurgent with inexpensive and powerful computing tools. Finally, an impressive level of activity was noted through the themes highlighted in this review, and this was particularly true with detectors and field instruments.

Multiresidue determination of pesticides in apples and pears by gas chromatography-mass spectrometry

This paper describes a rapid, specific and sensitive multiresidue method for the routine analysis of several classes of pesticides used for the treatment of apples and pears, involving a rapid extraction procedure at pH 4.5 with a mixture of acetone-dichloromethane-hexane (50:20:30, v/v/v) and gas chromatography coupled to mass-selective detection, in order to achieve quantitative analysis down to their respective maximum residue limit. Extraction recoveries were between 55 and 98%. Limits of detection and limits of quantitation ranged respectively, from 0.01 to 0.05 mg/kg and from 0.02 to 0.1 mg/kg. Intra-assay relative standard deviation was less than 19% for all compounds. An excellent linearity was observed from these LOQs up to 500 mg/kg. Intermediate (inter-assay) precision and accuracy were satisfactory. The method has been applied to many fruit samples intended for commercialisation.