Multiresidue Determination Of Pesticides Research Articles

Africanized honey bee colonies in Costa Rica: first evidence of its management, brood nest structure and factors associated with varroa mite infestation.

Management, brood nest structure and factors associated with varroa mite infestation were studied in 60 apiaries of Africanized honey bees in the northwest region of the Central Valley of Costa Rica. Apiaries were monitored two times. The first monitoring was taken forward during the rainy season between May and November 2019. The second monitoring during the dry season between February and March 2020. Information about the beekeepers, apiaries and management was collected through a survey. Amount of open and capped brood, honey and pollen were measured in the field. The infestation rate of varroa (IRV) was quantified using standard laboratory methods. A determination of multi-residue pesticides in bee bread was made through GC-MS/MS and LC-MS/MS techniques. According to the results, most of the beekeepers produce honey (96.7%), participate in training activities (82.2%), and change the bee queens annually (70%). The first monitoring was characterized by a lower amount of capped brood and honey reserves compared to the second one. IRV was significantly higher in the first monitoring (6.0 ± 0.4) in comparison with the second one (3.0 ± 0.3) (U Mann-Whitney p < 0.001). The maximum value for the first monitoring exceeds 40%, while this value was close to 25% in the second monitoring. Mite infestation exposed significant differences in relation to the variables associated to the beekeeper's management, i.e., change of bee queen (p = 0.002) or when beekeepers monitor varroa mites (p = 0.004). Additionally, the IRV had inverse correlations (p < 0.01) with the number of comb sides with capped brood (Spearman's rho coefficient = -0.190), and honey reserves (Spearman's rho coefficient = -0.168). Furthermore, 23 of 60 bee bread samples presented one to five pesticide residues, being the most frequent antifungal agrochemicals.

Multiresidue Determination of Pesticides in Potato Tuber, Peel, and Pulp by QuEChERS and UHPLC-MS/MS

Multiresidue Determination of Pesticides in Potato Tuber, Peel, and Pulp by QuEChERS and UHPLC-MS/MS

Combination of dispersive solid phase extraction with dispersive liquid–liquid microextraction for the determination of multi-residue pesticides from mango; Application of simplex centroid design in optimisation of the extractant composition

ABSTRACT A mixed mode dispersive solid phase extraction was introduced for the extraction of multi – class pesticides in mango samples. In the following, the extracted analytes were more concentrated by dispersive liquid – liquid microextraction. By the use of advantages of both sample preparation methods, the proposed analytical method was sensitive with high enrichment factors and less matrix effect. Some biopolymers including chitosan, agarose, and cellulose were employed as the sorbent in dispersive solid phase extraction due to their compatibility with the trends of green chemistry. The best composition of the biopolymers was obtained by a simplex centroid design and the data illustrated that the weight ratio of 4:1:1 (w/w/w) was the best composition of chitosan: agarose: cellulose for extraction of the pesticides, respectively. After optimisation of effective factors, the figures of merit were calculated. The validation data showed that the limit of detection were from 0.13 to 0.32 ng g−1. All of the calibration curves were linear in the range of 1.07–1000 ng g−1. The introduced method was successfully utilised for the extraction of the pesticides in mango samples. Fortunately, all studied samples were free of the analytes.

Multiresidue method for determination of pesticides in papaya using modified QuEChERS and UHPLC-MS/MS

ABSTRACT Papaya is the fourth most consumed fruit in Brazil and the third most exported fruit by the country. Considering that pesticides are frequently used in agriculture to increase production this work aimed to establish a method for the multiresidue determination of pesticides in papaya using the QuEChERS method and analysis by ultra-high performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS). The parameters that influence the extraction efficiency were studied and, after finding the best extraction conditions, the method was validated. The analysis by UHPLC-MS/MS allowed the determination of analytes with high selectivity and detectability. The main modification of the original QuEChERS method was the use of the polymeric sorbent Strata SDB-L in the clean-up step by dispersive solid-phase extraction. The method was validated for 110 compounds and presented adequate values of accuracy, with recoveries between 70 and 120%, and precision, with RSD<20%. The method limits of quantification ranged from 5 to 10 µg kg−1 and detection limits from 1.5 to 3 µg kg−1. The validated method was used for the determination of pesticides in commercial papaya samples, and 17 pesticides of different classes were found, including 5 pesticides not authorised in Brazil for papaya. Considering the results obtained, the use of the proposed method proved to be fast and efficient for the multiresidue determination of pesticides in papaya in routine analysis.

Competitive fluorescent immunosensor based on catalytic hairpin self-assembly for multiresidue detection of organophosphate pesticides in agricultural products

Simple and rapid multiresidue trace detection of organophosphate pesticides (OPs) is extremely important for various reasons, including food safety, environmental monitoring, and national health. Here, a catalytic hairpin self-assembly (CHA)-based competitive fluorescent immunosensor was developed to detect OPs in agricultural products, involving enabled dual signal amplification followed by a CHA reaction. The developed method could detect 0.01–50 ng/mL triazophos, parathion, and chlorpyrifos, with limits of detection (LODs) of 0.012, 0.0057, and 0.0074 ng/mL, respectively. The spiked recoveries of samples measured using this assay ranged from 82.8 % to 110.6 %, with CV values ranging between 5.5 % and 18.5 %. This finding suggests that the CHA-based competitive fluorescent immunosensor is a reliable and accurate method for detecting OPs in agricultural products. The results correlated well with those obtained from the liquid chromatography-tandem mass spectrometry (LC–MS/MS) method, indicating that the CHA-based biosensor is able to accurately detect OPs and can be used as a reliable alternative to the LC–MS/MS method. Additionally, the CHA-based biosensor is simpler and faster than LC–MS/MS, which makes it a more practical and cost-effective option for the detection of OPs. In summary, the CHA-based competitive fluorescent immunosensor can be considered a promising approach for trace analysis and multiresidue determination of pesticides, which can open up new horizons in the fields of food safety, environmental monitoring, and national health.

H-beta zeolite-based dispersive solid-phase strategy for the multi-residue determination of pesticides

In this work, electrostatic interactions, hydrogen bonding and other interactions between a variety of pesticides and H-beta zeolite are discussed based on thermodynamics (Gibbs free energy, enthalpy, and entropy). Combined with the physical properties of the target compounds (octanol-water partition coefficient and molar volume), the characteristics of the physical adsorption on the synthetic zeolite were analyzed, the results of H-beta zeolite adsorption showed that the adsorption rate had a nonlinear relationship with the physical properties, and the adsorption reaction was dominated by the adsorption on the surface and in the pores of the H-beta zeolite. Based on the principle of zeolite adsorption, the parameters of absorbent amount, adsorption time, sample pH, ion strength, sample volume and desorption solvent were optimized, a vortex-assisted dispersive solid-phase extraction procedure coupled with liquid chromatography-tandem mass spectrometry was developed for the analysis of multiple pesticides in surface water. The sample was adjusted by phosphate buffer or hydrochloric acid to pH 4, then adsorbed by 50 mg of zeolite within 10 min, adding 2% (g/v) sodium chloride to the solution. The absorbent was eluted with a mixture of acetonitrile-methanol containing 0.5% formic acid after separation, then filtered prior to analysis. The optimized vortex-assisted dispersive solid-phase extraction method simultaneously achieved a low adsorbent dosage, a high enrichment factor of 25, rapid pre-concentration for 30 min, a low solvent usage of 2 mL and multi-target simultaneous analysis. Method performance in terms of accuracy, precision, limit of detection, and limit of quantitation was performed to validate the reliability of the procedure. The proposed protocol achieved acceptable accuracy (recoveries between 62% and 107%), and precision (relative standard deviation < 20%). The limit of detection of the method was below 0.1 μg/L, and the limit of quantitation was 0.08 μg/L or 0.2 μg/L. The results indicated that zeolite is a promising adsorbent with high adsorption capacity. It has the advantages of being a fast, simple, green and economical method for determining residual pesticides in water.

An integrative review on the analysis of pesticide multiresidues in sweet pepper samples using the QuEChERS method and chromatographic techniques

Since foods are complex matrices that contain pesticides of different classes, multiresidue sample preparation methods such as QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe) are used and modified to obtain more accurate and sensitive results. This work was developed through an integrative review in the journal databases Capes, Science Direct, Scielo, and Scientia Chromatographic, from 2011 to 2021, to answer the following question: “What is the most efficient and advantageous sample preparation method for the determination of multiresidue pesticides of interest in sweet pepper samples, when chromatographic techniques are used for detection?” The sweet pepper was chosen because the Pesticide Residue Analysis in Food Program (PARA) suggests that it is the sample with the highest percentage of irregularities related to active ingredients not allowed or above the Maximum Residue Limit (MRL). A total of 391 articles were found, 11 of which met the inclusion criteria established. Several analyses were studied. The organophosphates were the most studied class of pesticide, with seven articles. In addition, there was a predominance of nonpolar analytes (log Kow &gt; 1). The use of different extracting solvents, such as methanol, acetonitrile, ethyl acetate, and acetone, was observed, with acetonitrile presenting the best analytical parameters in most cases. The use of different sorbents such as secondary and primary secondary amine (PSA), ocatadecyllane (C18), graphite carbon (GCB), and carbon black was noted, as well. The authors highlight the difficulties in the analysis when the matrix effect is significant (except for fensulfothion, tensulfothion, flonicamid, and its metabolite TFNA-AM) and the degradation of analytes through the analysis process (flonicamid, captan, folpet, thiophanate methyl and benomyl). Finally, the statistical test Analysis of Variance (ANOVA) was used to identify if there was a significant difference between the different methods used for the same analysis or when the same method used for the different analytes.

Multi-residue determination of pesticides in vegetables and assessment of human health risks in Western Himalayan region of India

This study was aimed to determine pesticides concentrations in fresh vegetables and assess human health risks in North-Western Himalayan region of India. Vegetable samples (n = 300) collected randomly from different agro-climatic zones were analyzed for 19 pesticides using gas chromatography. Pesticide residues were detected in 116 samples, of which 49 samples exceeded maximum permissible limits established by European Commission. Hexaconazole was most frequently detected in 9.3% samples followed by aldrin (8.3%), alachlor (5.3%), bifenthrin (4.3%), chlorpyrifos (3.7%), metribuzin (2.7%), β-endosulfan, ethion, β-HCH (2%, each), γ-HCH (1.3%), α-HCH, δ-HCH, malathion, heptachlor (1%, each), and α-endosulfan, pendimethalin in 0.7% samples. Human health risk assessment revealed that the percent contribution to acceptable daily intakes of pesticides via dietary intake of vegetables ranged from 0.014 to 39.4% in children and 0.003 to 9.85% in adults. Although hazard index values were < 1 but considering the concentrations of detected pesticide in samples, children were found to be at more risk. Since pragmatic investigations on occurrence of pesticides in vegetables and human health risk assessment from study area have not yet been worked out, so, this study highlights the importance of adopting good agricultural practices, awareness on food safety, monitoring of harmful chemicals in food commodities, and execution of food safety regulations to safeguard environmental and human health.

Simultaneous determination of 76 pesticide residues in the traditional Chinese medicine by magnetic hydrophilic-lipophilic-balanced materials assisted matrix solid phase dispersion extraction-high performance liquid chromatography-tandem mass spectrometry

建立灵敏、可靠的中药材中农药多残留的检测方法对保证中药材的质量和安全十分重要。制备了磁性亲水亲脂平衡萃取材料Fe3O4@PLS,将其应用于农药多残留的磁性基质固相分散萃取中,并结合高效液相色谱-串联质谱法(HPLC-MS/MS)检测了金银花、菊花和三七块根(干)3种中药材中76种农药残留量。研究通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)和X-射线衍射仪(XRD)对磁性萃取材料Fe3O4@PLS进行表面形貌和结构的表征。同时考察了影响磁性基质固相分散萃取效率的主要因素,结果表明,磁性萃取材料Fe3O4@PLS的用量为10 mg、研磨分散吸附时间为5 min、淋洗液为10 mL 20%(v/v)甲醇水溶液、涡旋振荡清洗1 min、以0.5 mL 0.1%(v/v)甲酸乙腈为洗脱剂、涡旋振荡洗脱1 min, 76种农药的萃取效果最佳。在实际应用中,76种农药在金银花、菊花、三七块根(干)3种中药材中的萃取回收率别为69.1%~112.2%、67.1%~102.8%和70.1%~105.1%,相对标准偏差分别为2.0%~12.4%、2.1%~13.2%和2.0%~13.5%。该方法利用Fe3O4@PLS良好的磁响应性和亲水亲脂通用吸附特性,可以同时萃取极性农药(如多菌灵等)和非极性农药(如敌瘟磷等),建立了测定中药材中76种农药残留的磁性基质固相分散萃取-高效液相色谱-串联质谱联用的分析方法,具有低消耗、操作简便、灵敏度高等优点,适用于非液态中药材基质中多种类农药残留的检测。

QuEChERS-based analytical methods developed for LC-MS/MS multiresidue determination of pesticides in representative crop fatty matrices: Olives and sunflower seeds

Oilseed crops are greatly extended all over the world. Their high fat content can interfere during pesticide multiresidue analysis through liquid chromatography-tandem mass spectrometry (LC-MS/MS). This work aimed at overcoming this issue by developing and validating two QuEChERS-based methods for LC-MS/MS determination of 42 pesticides in two fatty food matrices: olives and sunflower seeds. Optimization of the extraction method was achieved following a 26-2 fractional factorial design in a highly cost-effective way. Validation of the multi-residue methods demonstrated improved limits of detection, below the established maximum residue levels (MRLs) for almost all compounds, good precision, and trueness, in compliance with SANTE guidelines. Application of these methods to the analysis of real samples from the Iberian Peninsula showed the presence of some pesticides of relevant environmental concern, including four compounds contained in the Pesticide Action Network International list of highly hazardous pesticides, found at levels between 0.03 ng/g and 104 ng/g.

Determination of multi-pesticide residues in honey with a modified QuEChERS procedure followed by LC-MS/MS and GC-MS/MS

This paper presents a modified QuEChERS method to determine 346 pesticide residues in honey by LC/MS-MS and GC/MS-MS. Acetate buffered acetonitrile extraction followed by dispersive SPE clean-up with C18-E, PSA and MgSO4 sorbents were used for sample preparation. This method was validated according to the European Union SANTE/2019/12682 guidelines. Acceptable values were obtained for the linearity, the limit of detection (0.001–0.003 mg/kg), limit of quantification (0.002–0.008 mg/kg), trueness (for the four tested levels, the recovery assays values were between 76 and 112%), precision (RSD ≤20.0%) and measurement uncertainty tests (<50%). The method was used for the analysis of 100 honey samples from Northern Cyprus and residues of 4 pesticides (coumaphos, thiamethoxam, N-(2,4-dimethylphenyl)formamide, piperonyl butoxide) were quantified in 42 honey samples. Coumaphos (29%) and N-(2,4-dimethylphenyl)formamide (11%) were the residues frequently detected in the samples. N-(2,4-dimethylphenyl)formamide concentrations (0.56 and 0.84 mg/kg) were determined above the MRL limits (0.2 mg/kg) in two samples. This study shows that LC/MS-MS and GC/MS-MS in combination with modified QuEChERS can be used to routinely scan pesticide residues in honey samples and direct contamination with acaricides/veterinary drugs applied in the treatment of plagues in the hive during honey harvest is the main source of honey pollution in Northern Cyprus.

Monitoring of Pesticide Residues in Imported Datepalm Fruits in United Arab Emirates

The occurrence of pesticide residues in representative samples collected from imported dates palm fruits during 2020 to United Arab Emirates (UAE) was investigated to ensure compliance with the standard specifications and requirements by the regulatory and supervisory authorities, maintain the health and safety of consumers and improve food safety. An accurate, rapid, and reliable method for the simultaneous determination of pesticide multi-residues in 230 samples imported dates by liquid chromatography coupled with tandem mass spectrometry (LC–ESI (+)-MS/MS) operating in multiple reaction monitoring (MRM) mode and modified quick, easy, cheap, effective, rugged, safe (QuEChERS) method was used. The performance of the analytical method was validated in accordance with EU SANCO guidelines (SANTE/12682/2019) for monitoring pesticide multi-residues to check compliance with existing regulations, especially for European Community. Residues level of 343 compounds were determined in 230 samples. Results indicated that the percentage of samples with residues above the maximum residue levels (MRL) was 4.34% in dates samples, whereas samples with residues within MRL were 7.39% in dates samples. A total of 230 samples of 88.26% were free from detectable residues. Out of the 343 pesticides tested, 11 pesticides were found above the limit of detection, according to UAE, Codex, and European regulations. The main purpose of this work is to inform citizens and traders who have concerns about food safety on the capability of the MOCCAE on quality assurance regarding pesticide residue in imported food.

A multi-residue pesticide determination in fatty food commodities by modified QuEChERS approach and gas chromatography-tandem mass spectrometry

A QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) based multi-residue method has been developed and validated for the extraction and determination of pesticides in fatty matrices by gas chromatography tandem mass spectrometry. Extraction and clean-up were performed according to QuEChERS principles widely used for non-fatty matrices, with main difference, a higher solvent/sample- ratio followed by a 6-fold preconcentration step, ensuring good extractability and sensitivity. A validation according to SANTE guidelines was performed using a olive and sunflower oils mixture 1:1, w/w as representative matrix, at 2 concentration levels (5 and 50 µg/kg) targeting 176 GC-amenable pesticides. Most compounds fulfilled the validation criteria, with a limit of quantification of 5 µg/kg for 137 compounds , and of 50 µg/kg for 24 compounds. Afterwards, the method performance was tested in six different fatty matrices with 73–90% of the analytes fulfilling the performance criteria at 5 µg/kg depending on the matrix.

Determination of multi pesticide residues in leaf and needle samples using a modified QuEChERS approach and gas chromatography-tandem mass spectrometry.

In order to gain a better insight into pesticide and pollutant exposure in forests, a rapid and sensitive gas chromatography-tandem mass spectrometry (GC-MS/MS) method for the determination of 208 pesticide residues in leaves and needles has been established. The modified QuEChERS (quick, easy, cheap, effective, rugged and safe) approach uses 2 g of homogenized sample, acetonitrile and water as extraction agents, combined with citrate buffer for the following salting out step. The limits of quantification (LOQs) were determined to 0.0025-0.05 mg kg-1, respectively. Calibration curves showed a linear range between the respective LOQ and 1.0 mg kg-1 with coefficients of determination (R2) ≥ 0.99 for all analyzed pesticides. The recovery rates ranged from 69.7% to 92.0% with a relative standard deviation below 20%. The analysis of beech leaves, spruce and pine needles (each n = 3) provided a proof of concept for the developed methodology and revealed the presence of six pesticide residues (boscalid, epoxiconazole, fenpropimorph, lindane, terbuthylazine, terbuthylazine-desethyl). The results underline the strong need for systematic surveillance of the uncontrollable exposure of pesticides to nature.

Monitoring of Pesticide Residues in Imported Fruits and Vegetables in United Arab Emirates during 2019

An accurate, rapid and reliable method for the simultaneous determination of pesticide multi-residues in 9724 samples imported fresh fruits and vegetables by a method of liquid chromatography coupled with tandem mass spectrometry LC–ESI (+)-MS/MS operating in multiple reaction monitoring (MRM) mode, two transitions for each compound in the presence of internal standards and modified quick, easy, cheap, effective, rugged, safe (QuEChERS) method was used for the determination of 343 pesticides.&#x0D; The performance of the analytical method was validated in accordance with EU SANCO guidelines (SANTE/12682/2019) for monitoring pesticide multi-residues. Residues of 93 compounds, mainly fungicides and insecticides, were detected in 3548 samples.&#x0D; In this article, The potential applications of Liquid Chromatography and Tandem Mass spectrometry (MS/MS) techniques on monitoring pesticide residues of target samples of imported fruits and vegetables in United Arab Emirates (UAE) during the year 2019 is reported. The need for a continuous monitoring program of pesticide residues in imported fruits and vegetables is highly recommended and continuous process control for health and safety practices and to adhere to international agricultural and environmental policies of the country.

Multi-Residue Determination of Pesticides in Farmed Aquatic Animal Products Using Gas Chromatography-Tandem Mass Spectrometry

Multi-Residue Determination of Pesticides in Farmed Aquatic Animal Products Using Gas Chromatography-Tandem Mass Spectrometry

Mesoporous molecularly imprinted polymer core@shell hybrid silica nanoparticles as adsorbent in microextraction by packed sorbent for multiresidue determination of pesticides in apple juice

In this work, we report the synthesis of a mesoporous molecularly imprinted polymer on the surface of silica nanoparticles (core@mMIP) to be applied as adsorbent in microextraction by packed sorbent (MEPS) for selective determination of pesticides in apple juice. The core@mMIP was properly characterized, showing good adhesion of the polymer to the silica core. The best extraction conditions were: 200 µL of ultrapure water as washing solvent,150 µL of acetonitrile as eluent, 100 µL of sample at pH 2.5, five draw-eject cycles and 8 mg of adsorbent. Thereby, recoveries of 96.12 ± 1.05%, 76.88 ± 6.18% and 76.18 ± 5.57% were obtained for pyriproxyfen (PPX), deltamethrin (DTM) and etofenprox (ETF), respectively. After validation, the method presented linearity in the range of 0.02–10 µg mL−1 (r > 0.99), limit of detection of 0.005 µg mL−1, satisfactory selectivity, and proper precision and accuracy. The method was successfully applied real samples of processed and fresh apple juice.

Multi-residue determination of pesticides in green tea by gas chromatography-tandem mass spectrometry with atmospheric pressure chemical ionisation using nitrogen as the carrier gas

ABSTRACT Helium is commonly used as a carrier gas in gas chromatography-tandem mass spectrometry (GC-MS/MS); however, there are growing concerns regarding its global shortage and the resulting limited supply and high cost. Using nitrogen as an alternative carrier gas in GC-MS/MS with the widely used electron ionisation (EI) technique leads to a significantly lower sensitivity; thus, in this study, we explored the use of atmospheric-pressure chemical ionisation (APCI) as the ionisation method and examined the applicability of GC-(APCI)MS/MS with nitrogen gas for the determination of pesticide residues. GC-(APCI)MS/MS using nitrogen provided slightly wider peaks, and poorer isomeric separation compared to those using helium under identical conditions; however, the peak intensities were comparable. GC-(APCI)MS/MS using nitrogen was validated for 166 pesticides in green tea at a spiking level of 0.01 mg/kg and was compared with the conventional GC-(EI)MS/MS using helium gas. Except dimethomorph and resmethrin, GC-(APCI)MS/MS showed satisfactory results that were comparable to those of GC-(EI)MS/MS for most compounds, with trueness in the range of 73%–95% and relative standard deviations of <11%. The sensitivity and selectivity of GC-(APCI)MS/MS with nitrogen were superior to those of GC-(EI)MS/MS with helium. Therefore, GC-(APCI)MS/MS using nitrogen as the carrier gas, which has minimal concerns related to availability, could be a promising alternative to the conventional GC-(EI)MS/MS technique that employs helium.

Determination and Dietary Intake Risk Assessment of Pesticide Residues in Fritillariae Thunbergii Bulbs and Cultivated Soils.

Pesticide residues in traditional Chinese medicines pose a potential risk to human health. However, little is known about the characteristics of pesticide residues in the fritillariae thunbergii bulbs (FTB). This study aims to establish a method for the determination of pesticide multi-residues in FTB and then measured their residual levels in the FTB collected from nine cultivation regions. A modified QuEChERS method coupled with GC/UPLC was used to determine the residues of 24 pesticides in the FTB and soil samples. The recoveries of these pesticides at three concentrations were 72.17-112.48% in the FTB and 70.92-113.74% in the soil with RSD < 11.83%, and the LOD and LOQ ranged from 0.005-10 μg/kg and 0.011-22 μg/kg, respectively. A total of 13 pesticide residues were detected in the FTB samples with the residual levels of 0.0011-509.63 μg/kg, which were all below the referred MRLs in other Chinese herbs or food. Meanwhile, dietary intake risk assessment showed that the risk of pesticide residues in the FTB was acceptable to consumers. This study developed a method for the determination of pesticide multi-residues in the FTB and cultivated soil samples, and furthermore the dietary intake risk of pesticide residues in the FTB is safe. A modified QuEChERS method was established for the determination of 24 pesticides in the FTB with high sensitivity, accuracy, and precision.

Studies on multiresidue determination of pesticides in fruits and vegetables by gas chromatography/mass spectrometry

A multiresidue method using gas chromatography/mass spectrometry (GC/MS) was evaluated for the determination of several pesticides in fruits and vegetables. The pesticides were extracted using a slightly modified Luke multiresidue procedure, separated by capillary column gas chromatography and detected by mass chromatography with quadrupole mass spectrometer in the electron impact mode. Recovery studies of chlorpyrifos, diazinon, endosulfan, fenarimol, fenvalerate, folpet, iprodione, malathion, methamidophos, phosmet and procymidone were performed at the 0.5 ppm spike level in cherry tomatoes, chin-chian pe-tsai, Chinese cabbages, kidney beans and oranges. Recoveries were between 64.6 and 124.6%, with the exception of methamidophos which produced interference due to the constituents of the samples. Coefficients of variation ranged between 0.3 and 17.6%, with an average of 5.3%. The estimated limits of detection of the pesticides (except methamidophos) in the crops were at the 0.1 ppm level. Because the mass spectrometer is capable of achieving higher levels of molecular specificity as compared to the traditional GC detectors and can be programmed to search for several hundred target ions simultaneously, GC/MS may be a promising method for the use of regulatory agencies with which to monitor pesticide residues in daily food products.