Combination of dispersive solid‐phase extraction and salting‐out homogeneous liquid–liquid extraction for the determination of organophosphorus pesticides in cereal grains

A new analytical method for the determination of organophosphorus pesticides in cereal samples was developed by combining dispersive SPE (d‐SPE) and salting‐out homogeneous liquid–liquid extraction (SHLLE). The pesticides were first extracted from cereal grains with acetonitrile, followed by d‐SPE cleanup. A 2 mL aliquot of the extract was then added to a centrifuge tube containing 9.2 mL water and 3.3 g NaCl for SHLLE. Analysis of the extract was carried out by gas chromatography coupled with flame photometric detection. The d‐SPE procedure effectively provides the necessary cleanup of the extract while SHLLE is used as an efficient concentration technique. Experimental parameters influencing the extraction efficiency including amounts of added water and salt were investigated. Recovery studies were carried out at three fortification levels, yielding recoveries in the range of 57.7–98.1% with the RSD from 3.7 to 10.9%. The reported limits of determination obtained from this study were 1 μg/kg, which is better than the conventional methods. In the analysis of 40 wheat and corn samples taken from Beijing suburbs, only two wheat samples have chlorpyrifos residue over the limits of determination.     

Analytical method for 44 pesticide residues in spinach using multi‐plug‐filtration cleanup based on multiwalled carbon nanotubes with liquid chromatography and tandem mass spectrometry detection

Spinach is one of the most commonly planted vegetables worldwide. A high chlorophyll content makes spinach a complicated matrix in pesticide residue analysis. In this study, a rapid clean‐up method was developed for the analysis of pesticide multi‐residues in spinach followed by liquid chromatography with tandem mass spectrometry. A modified QuEChERS method with multiwalled carbon nanotubes and carbon material was adopted in the multi‐Plug Filtration Cleanup procedure. This method was validated for 44 representative pesticides spiked at two concentration levels of 10 and 100 μg/kg. The pesticides of different physicochemical properties were registered on spinach in China. The recoveries were between 76 and 114% for major pesticides with relative standard deviations of less than 15%, except for quizalofop‐P‐ethyl, pyrimethanil, and carbendazim. Matrix‐matched calibration curves were performed with the coefficients of determination higher than 0.995 for the studied pesticides for concentration levels of 10–500 μg/kg. The limits of quantitation ranged from 2 to 10 μg/kg. The developed method was successfully applied to determine pesticide residues in Chinese market spinach samples.     

Comparison of extraction solvents and sorbents in the quick,easy, cheap,effective, rugged,and safe method for the determination of pesticide multiresidue in fruits by ultra high performance liquid chromatography with tandem mass spectrometry

An improved analytical method was developed for the simultaneous quantification of several plant growth regulators and fungicides (carbendazim, pyrimethanil, metalaxyl, triadimefon, paclobutrazol, thiophanate, prochloraz, dimethomorph, difenoconazole, (4‐chlorophenoxy)‐acetic acid, (2,4‐dichlorophenoxy)‐acetic acid, thiadiazuron, forchlorfenuron and gibberellins) in fruits followed by ultra high performance liquid chromatography with tandem mass spectrometry. Samples were extracted and purified using a modified QuEChERS method. Different extraction solvents and sorbents in the QuEChERS method were compared. Optimum results were followed by the addition of 1% acetic acid in acetonitrile; C₁₈ sorbent was added due to the acidic nature of several pesticides. The recoveries of the pesticides were in the range 73.7–118.4%, with relative standard deviations lower than 16.63%. Limits of detection ranged from 0.1–1.0 μg/kg. The method presented here is simple, rapid, sensitive and can be applied to large‐scale monitoring programs to screen the presences of pesticides in fruits.     

Determination of multi‐pesticide residue in tobacco using multi‐walled carbon nanotubes as a reversed‐dispersive solid‐phase extraction sorbent

A multi‐pesticide residue determination method based on a modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) method using multiwalled carbon nanotubes as reversed‐dispersive solid‐phase extraction material was validated in 37 representative pesticides in tobacco. Determination was performed using liquid chromatography with tandem mass spectrometry in multiple reaction monitoring mode. Three major types of tobacco leaf samples, namely, flue‐cured, burley, and oriental tobacco were studied and compared. Three factors (extraction time, external diameter, and amount of extraction material used) that could affect the performance of multi‐walled carbon nanotubes were investigated. Optimization of sample preparation and determination allowed recoveries between 70.8 and 114.8% for all 37 pesticides with < 20.0% relative standard deviations at three spiking levels of 20, 50, and 200 μg/kg. The limits of quantification and limits of detection for the 37 pesticides ranged within 0.46–28.57 and 0.14–8.57 μg/kg at a signal‐to‐noise ratio of 10 and 3, respectively.     

Determination of 19 sulfonamides residues in pork samples by combining QuEChERS with dispersive liquid–liquid microextraction followed by UHPLC–MS/MS

A new simple and rapid pretreatment method for simultaneous determination of 19 sulfonamides in pork samples was developed through combining the QuEChERS method with dispersive liquid–liquid microextraction followed by ultra‐high performance liquid chromatography with tandem mass spectrometry. The sample preparation involves extraction/partitioning with QuEChERS method followed by dispersive liquid–liquid microextraction using tetrachloroethane as extractive solvent and the acetonitrile extract as dispersive solvent that obtained by QuEChERS. The enriched tetrachloroethane organic phase by dispersive liquid–liquid microextraction was evaporated, reconstituted with 100 μL acetonitrile/water (1:9 v/v) and injected into an ultra‐high performance liquid chromatography with a mobile phase composed of acetonitrile and 0.1% v/v formic acid under gradient elution and separated using a BHE C₁₈ column. Various parameters affecting the extraction efficiency were investigated. Matrix‐matched calibration curves were established. Good linear relationships were obtained for all analytes in a range of 2.0–100 μg/kg and the limits of detection were 0.04–0.49 μg/kg. Average recoveries at three spiking levels were in the range of 78.3–106.1% with relative standard deviations less than 12.7% (n = 6). The developed method was successfully applied to determine sulfonamide residues in pork samples.     

Rapid determination of residual pesticides in tobacco by the quick,easy, cheap,effective, rugged,and safe sample pretreatment method coupled with LC–MS

A quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample pretreatment method coupled with LC–MS was developed for the determination of 11 pesticides in tobacco. Sample pretreatment parameters and instrumental parameters of LC–MS were investigated, and the optimal conditions were selected. Under the optimized conditions, the 11 pesticides were detected simultaneously with a good linear relationship (r² = 0.9993–0.9999) and high precisions (less than 5% of the RSD of peak areas). The LODs were in the range of 0.1–5.0 μg/L. Compared with SPE clean‐up, QuEChERS greatly simplified the sample pretreatment with simple solvent extraction system. After QuEChERS pretreatment, no serious matrix effects were observed. Used for the analysis of real samples, metalaxyl was found in cigarette and tobacco samples at 63.47 and 132.27 ng/g, respectively. The recoveries for 11 pesticides were in the range of 70.03–118.69%, and RSDs were less than 10%. The proposed method is simple, low cost, and has good reproducibility.     

基于通过型固相萃取-超高效液相色谱-高分辨质谱同时测定杨梅中29种农药残留

建立了基于PRiME HLB通过型固相萃取净化-超高效液相色谱-高分辨质谱法(UPLC-HRMS)快速准确测定杨梅中29种常见农药残留的检测方法.杨梅样品经乙腈涡旋提取、盐析和PRiME HLB固相萃取净化后,以5mmol/L乙酸铵水溶液和乙腈溶液作为流动相在Waters ACQUITY UPLC HSS T3色谱柱(...     

Simultaneous preconcentration of polar and non‐polar organophosphorus pesticides from water samples by using a new sorbent based on mesoporous silica

A new mesoporous silica based on the sol–gel material cyanopropyltriethoxysilane (CNPrTEOS) was successfully synthesized by the hydrolysis and condensation of CNPrTEOS in the presence of ammonium solution as catalyst and methanol as solvent. It was used as a solid‐phase extraction sorbent for the simultaneous extraction of three organophosphorus pesticides, namely, polar dicrotophos and non‐polar diazinon and chlorpyrifos. Analysis was performed using high‐performance liquid chromatography with UV detection. CNPrTEOS was characterized by FTIR spectroscopy, field‐emission scanning electron microscopy and nitrogen gas adsorption. The surface area and average pore diameter of the optimum sol–gel CNPrTEOS are 379 m²/g and 4.7 nm (mesoporous), respectively. The proposed solid‐phase extraction based on CNPrTEOS exhibited good linearity in the range of 0.8–100 μg/L, satisfactory precision (1.15–3.82%), high enrichment factor (800) and low limit of detection (0.072–0.091 μg/L). The limits of detection obtained using the proposed solid‐phase extraction method are well below the maximum residue limit set by European Union and are also lower (13.6–48.5×) than that obtained by using a commercial CN‐SPE cartridge (0.98–4.41 μg/L). The new mesoporous sol–gel CNPrTEOS showed promising alternative as SPE sorbent material for the simultaneous extraction of polar and non‐polar organophosphorus pesticides.     

Comparison of several extraction procedures for the determination of biopesticides in soil samples by ultrahigh pressure LC-MS/MS

A new procedure has been proposed for the determination of biopesticides (nicotine, sabadine, veratridine, rotenone, azadirachtin, cevadine, deguelin, spynosad D, and pyrethrins) and piperonyl butoxide in agricultural soils. Several extraction procedures such as solid-liquid extraction using mechanical shaking, sonication, pressurized liquid extraction, and modified QuEChERS (quick, easy, cheap, effective, rugged, and safe) have been tested, obtaining better results when QuEChERS procedure without further cleanup steps was applied. The determination of the compounds was carried out by ultra high pressure liquid chromatography coupled to tandem mass spectrometry, using methanol and aqueous solution of ammonium formate 5 mM as mobile phase. The method was validated for all compounds at concentrations ranging from 10 to 100 μg/kg and recoveries ranged from 68 to 116%, except for nicotine and sabadine, with recoveries lower than 50%. Precision was estimated through intra- and inter-day studies, obtaining intra-day precision lower than 20% for most of the compounds, and inter-day precision was lower than 25%. Limits of detection and quantification were also estimated, obtaining limits of quantification equal or lower than 10 μg/kg. Finally, the method was applied to the analysis of 20 real agricultural soil samples and no biopesticide residues were found over the limit of quantification.     

Multi-residue determination of organophosphorus and organochlorine pesticides in environmental samples using solid-phase extraction with cigarette filter followed by gas chromatography-mass spectrometry

A solid‐phase extraction (SPE) method was developed to extract 14 pesticides simultaneously from environment samples using cigarette filter as the sorbent before gas chromatography‐mass spectrometry (GC‐MS) analysis. Parameters influencing the extraction efficiency, such as the sample loading flow rate, eluent and elution volume, were optimized. The optimum sample loading rate was 3 mL/min, and the retained compounds were eluted with 6 mL of eluent at 1 mL/min under vacuum. Good linearity was obtained for all the 14 pesticides (r²>0.99) from 0.1 to 20 μg/L for water and from 2 to 400 μg/kg for soil samples. The detection limits (signal‐to‐noise=3) of the proposed method ranged from 0.01 to 0.20 μg/L for water samples and from 0.42 to 6.95 μg/kg for soil samples. The developed method was successfully applied for determination of the analytes in real environmental samples, and the mean recoveries ranged from 76.4 to 103.7% for water samples and from 79.9 to 105.3% for soil samples with the precisions (relative standard deviation) between 2.0 and 13.6%.     

Trace analysis of some organophosphorus pesticides in rice samples using ultrasound‐assisted dispersive liquid–liquid microextraction and high‐performance liquid chromatography

An ultrasound‐assisted dispersive liquid–liquid microextraction based on solidification of a floating organic drop method followed by high‐performance liquid chromatography was developed for the extraction, preconcentration, and determination of trace amounts of organophosphorus pesticides in rice samples. Variables affecting the performance of both steps were thoroughly investigated. Some effective parameters on extraction were studied and optimized. Under the optimum conditions, recoveries for rice sample are in the range of 58.0–66.0%. The calibration graphs are linear in the range of 4–800 μg/kg and, limits of detection and limits of quantification are in the range of 1.5–3 and 4.2–8.5 μg/kg, respectively. The relative standard deviation for 50.0 μg/kg of organophosphorus pesticides in rice sample are in the range of 4.4–5.1% (n = 5). The obtained results show that proposed method is a fast and simple method for the determination of pesticides in cereals.     

Combination of the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method and dispersive liquid-liquid microextraction in the identification and determination of pesticides from various classes in food products by gas-liquid chromatography

A procedure for the identification (104 substances) and determination (40 substances) of the active components of combined pesticides from different classes in water, vegetables, fruits, and meat by gas chromatography with mass-spectrometric and electron-capture detectors was proposed. The pesticides were extracted from the samples of vegetables, fruits, and meat with acetonitrile using the QuEChERS method. The extracts were preconcentrated by a factor of 50–60 and additionally purified by dispersive liquid-liquid microextraction. The pesticides were extracted from water by dispersive liquid-liquid microextraction with hexane (degree of concentration was higher than 100). The limits of detection by the time-of-flight detector equaled 0.01–0.02 mg/kg for solid samples and 1–2 μg/L for aqueous solutions. The limits of quantitation for pesticides were 1–2 mg/kg for solid samples and 0.05–0.1 μg/L for solutions. The analysis time was 1–2 h, and the RSD of the results did not exceed 18%.     

A new solid-phase extraction and HPLC method for determination of patulin in apple products and hawthorn juice in China

A new solid‐phase extraction (SPE) pretreatment method using a home‐made polyvinylpolypyrrolidone‐florisil (PVPP‐F) column was developed for the analysis of patulin in apple and hawthorn products in China. Fifty samples (25 apple juices, 12 apple jams, and 13 hawthorn juices) were prepared using the new method and then analyzed by high performance liquid chromatography with diode array detection (HPLC‐DAD) on an Agela Venusil MP C₁₈ reversed‐phase column (4.6 mm × 250 mm, 5 μm). The cleanup results for all samples using home‐made PVPP‐F column were compared with those obtained using a MycoSep®228 AflaPat column. The correlation coefficient R (0.9998) fulfilled the requirement of linearity for patulin in the concentration range of 2.5–250 μg/kg. The limits of detection (LODs) and quantification (LOQs) of patulin were 3.99 and 9.64 μg/kg for PVPP‐F column, and 3.56 and 8.07 μg/kg for MycoSep®228 AflaPat column, respectively. Samples were spiked with patulin at levels ranging from 25 to 250 μg/kg, and recoveries using PVPP‐F and MycoSep®228 AflaPat columns were in the range of 81.9–100.9% and 86.4–103.9%, respectively. Naturally occurring patulin was found in 2 of 25 apple juice samples (8.0%) and 1 of 13 hawthorn juice samples (7.7%) at concentrations ranging from 12.26 to 36.81 μg/kg. The positive results were further confirmed by liquid chromatography electrospray ionization mass spectrometry (LC‐ESI‐MS).     

Simultaneous separation and determination of eight organophosphorous pesticide residues in vegetables through molecularly imprinted solid‐phase extraction coupled to gas chromatography

How to determine the multipesticide residues in vegetables is an important problem. In this study, a new molecularly imprinted polymer was synthesized using O,O‐dimethyl thiophosphoryl chloride, an intermediate for the manufacture of organophosphorous pesticides, as the template. Characterization test indicated that the synthesized polymer exhibited good recognition and selectivity for dichlorvos, methamidophos, acephate, folimat, monocrotophos, parathion‐methyl, phosphamidon, and malathion. A molecularly imprinted SPE coupled to GC for simultaneous separation and determination of eight organophosphorous pesticides residues was developed. Under optimal conditions, the linear range of this method was 0.001–10.0 mg/L. The LOD of this method was in the range of 0.13–0.90 μg/kg. With a flow rate of 2.5 mL/min for loading 100 mL, the enrichment factor in the range of 25–480 for the eight organophosphorous pesticides was obtained. The RSD of the eight organophosphorous pesticides based on five replicates was from 1.50 to 4.09%. The accuracy of the proposed method was evaluated by recovery measurements on spiked samples, and good recovery rates ranging from 80.11 to 97.70% were achieved. Moreover, this method was evaluated for the quantitative detection of eight organophosphorous pesticide residues in leek and pakchoi samples.     

Quantification of five neonicotinoids in human urine by modified QuEChERS with isotope dilution mass spectrometry: a preliminary study for the development of certified reference material

ABSTRACT

A study for the quantification method of neonicotinoid pesticides (Neos) in human urine that aims to develop the certified reference material (CRM) in the future was carried out. A modified Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) method based on dispersive solid phase extraction (d-SPE) with isotope dilution mass spectrometry (IDMS) was evaluated for the quantification of five Neos (acetamiprid, dinotefuran, imidacloprid, thiacloprid and thiamethoxam) in human urine control by optimisation of the extraction solvent, and the type and amount of d-SPE material. Two types of human urine controls (sample A and B) containing 5 μg/kg and/or 25 μg/kg of Neos were prepared and employed for this study. The results of spike test using sample A (2 mL) obtained by modified QuEChERS method with acetone extraction (10 mL) and d-SPE using a strong cation exchanger (silica gel modified with benzenesulphonic acid phase, SCX) 500 mg were as follows: 97.8%–103.1% for 5 μg/kg and 97.2%–102.7% for 25 μg/kg (described as percentage by the quantification results of IDMS relative to the spiked amount of pesticides). These results were comparable to those by SPE cartridge method using SCX functionalised hydrophilic styrene divinylbenzene (PCX). The repeatabilities of the analyses, represented as relative standard deviations, were also comparable for spike level 5 μg/kg and 25 μg/kg of Neos: 0.1%–7.2% for modified QuEChERS with IDMS and 0.2%–5.6% for PCX cartridge method. The results of spike test using sample B for a spike level 5 μg/kg were 96.0%–100.6%. These results indicate that modified QuEChERS method with IDMS can be used for the development of certified reference material and has the potential to use for the quantification of Neos in real human urine.     

Fast ultrasound‐assisted extraction followed by capillary gas chromatography combined with nitrogen–phosphorous selective detector for the trace determination of tebuconazole in garlic,soil and water samples

A fast and an efficient ultrasound‐assisted extraction technique using a lower density extraction solvent than water was developed for the trace‐level determination of tebuconazole in garlic, soil and water samples followed by capillary gas chromatography combined with nitrogen–phosphorous selective detector (GC–NPD). In this approach, ultrasound radiation was applied to accelerate the emulsification of the ethyl acetate in aqueous samples to enhance the extraction efficiency of tebuconazole without requiring extra partitioning or cleaning, and the use of capillary GC–NPD was a more sensitive detection technique for organonitrogen pesticides. The experimental results indicate an excellent linear relationship between peak area and concentration obtained in the range 1–50 μg/kg or μg/L. The limit of detection (S/N, 3 ± 0.5) and limit of quantification (S/N, 7.5 ± 2.5) were obtained in the range 0.2–3 and 1–10 μg/kg or μg/L. Good spiked recoveries were achieved from ranges 95.55–101.26%, 96.28–99.33% and 95.04–105.15% in garlic, Nanivaliyal soil and Par River water, respectively, at levels 5 and 20 μg/kg or μg/L, and the method precision (% RSD) was ≤5%. Our results demonstrate that the proposed technique is a viable alternative for the determination of tebuconazole in complex samples.     

Development of a procedure for the multiresidue analysis of pesticides in vineyard soils and its application to real samples

A procedure for multiresidue analysis was developed for the extraction and determination of 17 pesticides, including herbicides, fungicides, and insecticides, as well as certain degradation products, in vineyard soils from La Rioja region (Spain). Different solvents and mixtures were tested in spiked pesticide‐free soils, and pesticides were comparatively evaluated by gas chromatography with mass spectrometry and liquid chromatography with mass spectrometry. Recoveries >70%, with relative standard deviations <9%, were obtained when a mixture of methanol/acetone or a mixture of methanol/CaCl₂ 0.01 M for the most polar compounds was selected as the extraction solvent. Method validation was accomplished with acceptable linearity (r² ≥ 0.987) within the concentration range of 0.005–1 μg/mL corresponding to 1.667–333.4 μg/kg and 0.835–167.1 μg/kg for liquid chromatography with mass spectrometry and gas chromatography with mass spectrometry, respectively, and detection limits <0.4 μg/kg for the compounds were studied. The extraction method was applied to 17 real vineyard soil samples, and terbuthylazine and its metabolite desethylterbuthylazine were the most ubiquitous compounds, as they were detected in the 100% of the soils analyzed. The presence of fungicides was also high, and the presence of insecticides was lower than other pesticides. The results confirm the usefulness of the optimized procedure for monitoring residues in vineyard soils.     

Method for routine screening of pesticides and metabolites in meat based baby‐food using extraction and gas chromatography‐mass spectrometry

A simple and complete multiresidue method has been developed for the routine determination of 236 pesticides and degradation products, in meat based baby‐food. This original approach combines a modified Quick Easy Cheap Effective Rugged and Safe (QuEChERS) sample preparation method using a triple partitioning extraction step with water/ACN/hexane and a system composed of GC with programmable temperature vaporization injector hyphenated to an IT‐MS. Detection was performed in full scan mode, with one quantification ion and one identification ion. We firstly report here the hexane addition in the extraction step to eliminate a major part of lipophile co‐extracts. Direct consequences were the increasing of method sensitivity and the diminishment of the frequency of maintenance of the analytical instrument. The recovery data were obtained by spiking blank samples at three concentration levels (10, 50 and 200 μg/kg) over five replicates, yielding average recoveries in the range 70–121% with a RSD evaluated between 2–15%. Linearity was fixed in the range of 10–300 μg/kg with determination coefficients (R²) superior or equal to 0.9814 for all target analytes. Best LODs and LOQs were established as 0.03 and 0.1 μg/kg, respectively. Total instrumental analysis of all molecules was carried out in less than 1 h.     

Analysis of insecticides in honey by liquid chromatography-ion trap-mass spectrometry: comparison of different extraction procedures

The feasibility of different extraction procedures was tested and compared for the determination of 12 organophosphorus and carbamates insecticides in honey samples. In this sense, once the samples were pre-treated - essentially dissolved in hot water by stirring - and before they could be analyzed by liquid chromatography-ion trap-second stage mass spectrometry (LC-MS(2)), four different approaches were studied for the extraction step: QuEChERS, solid-phase extraction (SPE), pressurized liquid extraction (PLE) and solid-phase microextraction (SPME). The main aim of this work was to maximise the sensitivity of pesticides and to minimise the presence of interfering compounds in the extract. All pesticides were linear in the range from CC(β) to 1000× CC(β) for the four extraction methods (three orders of magnitude). Detection capabilities (CC(β)) were 0.024-1.155 mg kg(-1) with QuEChERS, 0.010-0.646 mg kg(-1) with SPE, 0.007-0.595 mg kg(-1) with PLE, and 0.001-0.060 mg kg(-1) with SPME. All the target compounds could be recovered by any of the methods, at a CC(β) fortification level ranged from 28 to 90% for the SPME. In comparison, the PLE method was the most efficient extraction method with recoveries from 82 to 104%. It was followed by the QuEChERS method with recoveries between 78 and 101% and the SPE method with recoveries between 72 and 100%. The repeatability expressed as relative standard deviation (RSDs) was below 20% for all the pesticides by any of the tested extraction methods. Results obtained applying the four extraction techniques to real honey samples are analogous.     

Optimization of QuEChERS method for the analysis of organochlorine pesticides in soils with diverse organic matter

A QuEChERS method has been developed for the determination of 14 organochlorine pesticides in 14 soils from different Portuguese regions with wide range composition. The extracts were analysed by GC-ECD (where GC-ECD is gas chromatography-electron-capture detector) and confirmed by GC-MS/MS (where MS/MS is tandem mass spectrometry). The organic matter content is a key factor in the process efficiency. An optimization was carried out according to soils organic carbon level, divided in two groups: HS (organic carbon >2.3%) and LS (organic carbon <2.3%). The method was validated through linearity, recovery, precision and accuracy studies. The quantification was carried out using a matrix-matched calibration to minimize the existence of the matrix effect. Acceptable recoveries were obtained (70-120%) with a relative standard deviation of ≤16% for the three levels of contamination. The ranges of the limits of detection and of the limits of quantification in soils HS were from 3.42 to 23.77 μg kg(-1) and from 11.41 to 79.23 μg kg(-1), respectively. For LS soils, the limits of detection ranged from 6.11 to 14.78 μg kg(-1) and the limits of quantification from 20.37 to 49.27 μg kg(-1) . In the 14 collected soil samples only one showed a residue of dieldrin (45.36 μg kg(-1) ) above the limit of quantification. This methodology combines the advantages of QuEChERS, GC-ECD detection and GC-MS/MS confirmation producing a very rapid, sensitive and reliable procedure which can be applied in routine analytical laboratories.