Gas Chromatography-electron Capture Detection Research Articles

Simultaneous Determination of Atrazine, Pendimethalin, and Trifluralin in Fish Samples by QuEChERS Extraction Coupled With Gas Chromatography-Electron Capture Detection

A rapid, simple, and dependable method was developed and validated for the simultaneous determination of atrazine, pendimethalin, and trifluralin in fish samples. Target analytes were extracted and purified by the modified QuEChERS method prior to analysis. Ultrasound-assisted extraction (10 min) was used to improve the extraction efficiency of classical acetonitrile extraction. The organic phase was then cleaned using dispersive solid-phase extraction with 150 mg primary secondary amine and 100 mg C18-bonded silica sorbents. GC with electron capture detection was used for determination. The method resulted in good linearity (R2 = 0.9973–0.9998) and low limits of detection and quantification (0.015–0.60 and 0.050–2.0 μg kg−1). Recoveries ranged from 76.8 to 94.6% with repeatability between 2.3 and 3.8% and reproducibility between 3.4 and 4.8%. The performance parameters demonstrated the method adequacy for the detection and quantification of atrazine, pendimethalin, and trifluralin residues in freshwater fish.

Biological Monitoring of the Oncology Healthcare Staff Exposed to Cyclophosphamide in Two Hospitals in Tehran

Background: Antineoplastic drugs as chemotherapy agents are used for various therapeutic purposes. Occupational exposure to antineoplastic drugs is possible through inhalation, skin contact, skin absorption, and digestive or injection. Assessment of occupational exposure of staff working with anti-neoplastic drugs has been a major concern among practitioners and occupational health and safety managers. Objectives: Considering the importance of safeguarding oncology personnel against antineoplastic drugs, the aim of this study was to validate a method for analysing cyclophosphamide (CPA) in urine samples as the biomarker of the exposure of oncology personnel of two hospitals in Tehran. Methods: Standard urine samples were obtained from a healthy man without having any exposure to CPA drug. The standards urine samples of CPA within the concentration range of 0.02 to 50 microgram per liter (µg/L) were prepared by diluting the urine stock solution. Ifosfamide (IFO) was added as an internal standard at a concentration of 20 µg/L. CPA and IFO analysis by gas chromatography-electron capture detector (GC-ECD) in this study was confirmed by gas chromatography-mass spectrometry (GC-MS) for verification of their peak retention times and MS signature at 95% confidence. Results: Urinary CPA concentrations as the biomarker of the exposure of the oncology personnel were detected within the range of 0.52 to 21.4 µg/L. The drug presence in the urine of 31% (10 of 32) of two hospital staff indicate the biological monitoring potential to recognition of worker’s exposure. Conclusions: In general, biological monitoring of oncology personnel could be a useful tool for assessing occupational exposure through all routes and efficacy of the current safety measures. Owing to higher values of urinary CPA in this study compared to the studies of their colleagues abroad stringent control measures were deemed necessary.

An evaluation of the levels of organochlorine compounds (OCPs and PCBs) in cultured freshwater and wild sea fish eggs as an exposure biomarker for environmental contamination.

In this study, the eggs of 30 wild Black Sea whiting (Merlangius merlangus euxinus, Nordmann, 1840) and 30 farmed freshwater rainbow trout (Oncorhynchus mykiss, Walbaum, 1792) collected from Samsun Province in Turkey were analyzed to determine the level of contamination by nine organochlorine pesticides (OCPs), namely α-hexachlorocyclohexane (α-HCH), β-HCH, γ-HCH (lindane), hexachlorobenzene (HCB), aldrin, 2,4'-dichlorodiphenyltrichloroethane (DDT), 4,4'-DDT, 2,4'-dichlorodiphenyldichloroethylene (DDE), 4,4'-DDE, and 15 polychlorinated biphenyls (PCBs) (PCB-28, -70, -74, -81, -99, -101, -118, -138, -153, -156, -170, -180, -183, -187, and -208), and their potential use as biomarkers to monitor levels of environmental contamination. OCPs and PCBs in the fat of fish eggs were extracted cryogenically and their concentrations were determined with a gas chromatography-electron capture detector (GC-ECD). The whiting eggs showed high OCP and PCB levels compared to the rainbow trout eggs. The median ∑ DDT values for whiting and rainbow trout eggs were 1601.62ngg-1 fat (range 824.87-5049.81) and 406.49ngg-1 fat (range 199.88-588.82); median ∑Indicator PCBs were 1264.24ngg-1 fat (range 520.05-6140.32) and 82.11ngg-1 fat (range 2.85-215.97); and median ∑ HCHs were 155.66ngg-1 fat (range 35.45-330.40) and 13.48ngg-1 fat (range 4.44-66.44), respectively. In the whiting eggs, the ∑Indicator PCB level was above the maximum residue limit (MRL) of 200ngg-1 fat stated in the European Commission Regulation (EC) and Turkish Food Codex (TFC). In addition, there was a significant difference between the contamination levels of the eggs of the two species. In conclusion, it appears that fish eggs can serve as a valuable biomarker for the level of contamination of persistent organochlorine contaminants in different aquatic environments.

Persistence of pesticides in green vegetables of Satna District of Madhya Pradesh

Astudy was conducted forthe qualitative and quantitative estimation of 51 pesticides comprising 16 organochlorines, 23 organophosphates, eight synthetic pyrethroids and four herbicides in commonly consumed green vegetables i.e spinach, coriander, chilli, ladyfinger, bottle gourd and bitter gourd collected from various tehsils of Satna district, Madhya Pradesh. Gas chromatography-Electron Capture Detector (GC-ECD), Flame Photometric Detector (GC-FPD) were used for estimation of pesticides and Gas chromatography-Mass Spectrometry (GC-MS) was used for confirmation. Out of 144 samples, 59 samples were found contaminated with pesticide residue. It was observed that most of the bitter gourd samples were contaminated with chlorpyrifos whereas spinach and okra were contaminated with cypermethrin. Nagod samples were found most contaminated (10 out of 18) whereas Rampur Baghelan were least contaminated (6 out of 18). Contamination of chlorpyrifos was predominant in samples of Nagod, Raghurajnagar and Birsinghpur whereas cypermethrin contamination was so in Majhagawa samples. Profenofos and monocrotophos were detected only in Nagod and Raghurajnagar samples.

Pyrethroids residues analysis in Indonesian commercial tea by GC-ECD

Monitoring of pesticides residue including pyrethroids is required since they are major contaminants in tea and have been regulated in European Union and countries such as China, Australia, Japan and America. This study aimed to analyze several pyrethroids in Indonesian commercial tea. The analysis was done by applying low volume solid-liquid extraction followed by quantification by gas chromatography-electron capture detector as a relatively cheaper alternative instrument in pesticides monitoring compared to mass spectrophotometer. The detection limits of the method were 0.006 mg/kg for deltamethrin, 0.05 mg/kg for fenvalerate, 0.10 mg/kg for cypermethrin and 0.05 mg/kg for λ-cyhalothrin. The linearity of the method was good with coefficient correlation of higher than 0.997 at 0.3 to 2.0 mg/kg. The repeatability of the method was also good with lower % relative standard deviations compared to two-thirds of Horwitz coefficient of variation and European Commission guideline. The recoveries were all in the range suggested by European Commission. Weak matrix effect was observed for deltamethrin and cypermethrin while matrix suppression effect was observed for λ-cyhalothrin and fenvalerate. Analysis of tea samples planted and produced in Indonesia showed that the pyrethroid residue in the samples were all below the maximum residue limits while the risk assessment suggested that Indonesian commercial tea is safe for consumption.

Analysis for Organochlorine Pesticide Residues in Honey from Kabale District, South-Western Uganda

This study was motivated by the reported accumulation of Organochlorine Pesticides (OCPs) residues in the various environmental matrices within Uganda, resulting from their use in agriculture and health sectors. This raised a concern of the likelihood of the accumulation of the OCPs residues in the honey produced within the country which would affect its purity as well as quality and consequently its competition on the world market. Sixty representative honey samples were collected from selected local beekeepers from four sampling stations in Muko sub-county, Kabale, and extracted for OCPs using a solid-phase procedure followed by a florisil column packed clean-up method and Gas Chromatography-Electron Capture Detector (GC-ECD) analysis. Confirmation of the selected samples was done using an Agilent (6890N, USA) gas chromatograph combined with a mass spectrometer. Recoveries of spiked samples ranged from 71% to 96%, except for pp-DDE (54%), with relative standard deviations from 2% to 14% in terms of repeatability, and from 4% to 17% in terms of reproducibility. Limits of quantification were from 0.003 to 0.1 mg·kg-1. Endosulfan sulfate was the most frequently detected in 38% of the samples, followed by HexaChloroBenzene (Lindane) in 21% of the samples. Residues of DDT and their metabolites were detected in 17% of the samples. Mean concentrations of the pesticide residues detected range from ND (not detected) to 1.53 μg/Kg. The acceptable Maximum residual limits (MLRs) are 200 - 300 μg·kg-1 fresh weight for dieldrin, 500 μg·kg-1 for DDT and break down products, and 50 μg·kg-1 wet weight for Lindane (WHO/FAO 2011). Results indicate that the levels of OCP residues detected in honey from the country’s South Western District of Kabale were within the acceptable limits, and hence this honey was safe for human consumption.

Fe3O4 nanoparticle-modified multi-walled carbon nanotubes for the determination of synthetic pyrethroids in human blood

In this study, a sensitive and rapid magnetic solid-phase microextraction (MSPE) procedure based on Fe3O4 nanoparticle-modified, multi-walled carbon nanotubes combined with a gas chromatography/electron capture detector (GC/ECD) was developed to quantify pyrethroids in human blood samples. This study compared liquid–liquid extraction and solid-phase extraction methods and found that the MSPE-GC/ECD method had many advantages, such as high recovery rate, high extraction efficiency, high detection sensitivity, low limit of detection, and simple operation. It can meet the actual requirements for the determination of synthetic pyrethroids in human blood.

Co- and self-activated synthesis of tailored multimodal porous carbons for solid-phase microextraction of chlorobenzenes and polychlorinated biphenyls

Highly sensitive solid-phase microextraction (SPME) of broad-spectrum organic micropollutants is a significant challenge due to the limited available pore sizes and pore size distributions (PSDs) of the probes. In this work, we synthesized novel multimodal porous carbons (MPCs) using facile and environment-friendly route for the first time, through direct carbonization of a potassium citrate and calcium citrate mixture. The co-carbonization process formed hierarchical structures with super-high specific surface areas (up to 3270 m2 g−1) and pore volumes (up to 1.79 cm3 g−1). The PSD was easily controlled through adjustment of the mixture ratios of potassium citrate to calcium citrate. Moreover, the MPCs were partly graphitized, and showed great thermal stability (>450 ℃). MPC-coated probes were prepared and applied to extract chlorobenzenes (CBs) and polychlorinated biphenyls (PCBs) with improved performance, higher extraction capacity than commercial carboxen/polydimethylsiloxane probe. Under optimized conditions, a sensitive detection method for CBs and PCBs was developed by a MPC-coated probe coupled with gas chromatography-electron capture detector. Finally, this method was successfully applied to analyze real environmental water samples with satisfactory recoveries (85.56%–104.30%). The findings are expected to broaden our perspectives for improved design of efficient porous materials for broad-spectrum SPME and other applications.

Analysis of Multi-Residue Pesticides in Vegetable Samples Using Solid-Phase Micro-Extraction (SPME) Coupled to Gas Chromatography-Electron-Capture Detector (GC-ECD)

A fast, simple, solvent less and inexpensive sample preparation method based on Head space solid-phase micro extraction (HS-SPME) coupled to gas chromatography-electron-capture detector (GC-ECD) is proposed for the determination of mix pesticide residues from vegetable samples. Polydimethylsiloxane (PDMS, 100 μm) fiber was used in this study. The mix pesticides (24 nos.) including organochlorines (15), organophosphates (06) and synthetic pyrethriods (03) were analysed in the vegetable samples (Cabbage, Tomato, Cauliflower, Chilli, Okra, Brinjal, Bottle gourd, Cucumber, Beetroot, Spinach, and Radish) collected from in and around of Lucknow city, India. Present study revealed the presence of HCH, DDT, methylparathion, malathion, chlorpyrifos, monocrotophos, endosulfan, cypermethrin, fenvalerate pesticides. Pesticides residue levels were compared with MRL fixed by Prevention of Food Adulteration Act (PFA), Govt. of India 1954. The method detection limits were in a linearity range of 0.003 - 0.024 mg/kg. A recovery percent varies from 86.1 to 96.4% with relative standard deviation (RSD) of 14%. The outcomes of the present study point towards the crucial need of implementing strict government’s rules related to food safety in order to put check on these kinds of health hazardous food contamination.

Determinants of pesticide concentrations in silicone wristbands worn by Latina adolescent girls in a California farmworker community: The COSECHA youth participatory action study

Personal exposure to pesticides has not been well characterized, especially among adolescents. We used silicone wristbands to assess pesticide exposure in 14 to 16 year old Latina girls (N = 97) living in the agricultural Salinas Valley, California, USA and enrolled in the COSECHA (CHAMACOS of Salinas Examining Chemicals in Homes and Agriculture) Study, a youth participatory action study in an agricultural region of California. We determined pesticide concentrations (ng/g/day) in silicone wristbands worn for one week using gas chromatography electron capture detection and employed gas chromatography mass spectrometry to determine the presence or absence of over 1500 chemicals. Predictors of pesticide detections and concentrations were identified using logistic regression, Wilcoxon rank sum tests, and Tobit regression models. The most frequently detected pesticides in wristbands were fipronil sulfide (87%), cypermethrin (56%), dichlorodiphenyldichloroethylene (DDE) (56%), dacthal (53%), and trans-permethrin (52%). Living within 100 m of active agricultural fields, having carpeting in the home, and having an exterminator treat the home in the past six months were associated with higher odds of detecting certain pesticides. Permethrin concentrations were lower for participants who cleaned their homes daily (GM: 1.9 vs. 6.8 ng/g/day, p = 0.01). In multivariable regression models, participants with doormats in the entryway of their home had lower concentrations (p < 0.05) of cypermethrin (87%), permethrin (99%), fipronil sulfide (69%) and DDE (75%). The results suggest that both nearby agricultural pesticide use and individual behaviors are associated with pesticide exposures.

Detection of halogenated hydrocarbon pollutants using enzymatic reflectance biosensor

A reflectometric biosensor for enzymatic determination of halogenated organic pollutant in environmental water sample was developed. Polyacrylate microspheres modified with succinimide functional groups were employed as the substrate matrix for covalent immobilization of haloalkane dehalogenase (DhlA) enzyme, and ETH5294 Nile Blue chromoionophore (NBC) pH dye was physically immobilized on the acrylic micromatrix to function as an optical proton sensor. The hydrolytic dehalogenation of halocarbon catalyzed by the immobilized DhlA resulting in the release of a halogen and a proton, which protonated the immobilized NBC proton indicator, and a colour change of the biosensor from violet to blue was measured with a reflectance spectrophotometer for indirect quantification of the halogenated hydrocarbon concentration. The enzymatic halocarbon reflectance biosensor exhibited a dynamic linear response range of 1–30 mg L−1 1,2-dichloroethane (DCA) (R2 = 0.9762) with a detection limit of 0.3 mg L−1. The proposed enzymatic biosensor gave rapid response, within 2 min, towards the detection of 50 mg L−1 DCA at 662 nm, and demonstrated stable response up to 6 days of storage period at 4 °C and pH 8.0. Validation between the developed biosensor with standard gas chromatography–electron capture detector (GC-ECD) showed that both methods have a comparable accuracy in detecting halocarbon species.

Organochlorine pesticide residues in sediment and water from Nairobi River, Kenya: levels, distribution, and ecological risk assessment.

Production and use of most organochlorine pesticides (OCPs) was banned through the Stockholm Convention on persistent organic pollutants. However, appreciable amounts are still detected in the environment due to their persistence, illegal use, and releases from contaminated soils and obsolete stocks. The present study investigated the levels of OCP residues in Nairobi River. Sediment and water samples were collected from three sites along the river and screened for 17 OCPs using gas chromatography electron capture detector (GC-ECD). Mean pesticide residues ranged from 0.01 to 41.9μgkg-1 in sediment and below detection limit to 39.7ngL-1 in water. In sediment α-HCH, β-HCH, γ-HCH, heptachlor epoxide, and p,p'-DDD were detected in all samples, while α-HCH, γ-HCH, δ-HCH, heptachlor epoxide, endosulfan I, and endrin were detected in all water samples. Levels of OCPs in water were below the WHO maximum allowable limits for surface water. However, values higher than the sediment quality guidelines for sediment samples in Racecourse Road Bridge and Outering Road Bridge were reported, thus confirming the toxicity to aquatic organisms. Consequently, as these compounds are known to bio-accumulate in fatty tissues, continued use of the river water poses a health risk to animals and humans.

Determination of pesticides residues in vegetable and fruit samples by solid-phase microextraction with a covalent organic framework as the fiber coating coupled with gas chromatography and electron capture detection.

In this study, a covalent organic framework designated as TpPaNO2 was synthesized by a mechanochemical grinding method and then coated on stainless steel wire by a sol-gel technique to prepare a solid-phase microextraction fiber. The TpPaNO2 fiber based solid-phase microextraction coupled with gas chromatography-electron capture detection was applied to determine the residues of 11 pesticides (trlfuralln, dicofol, α-endosulfan, 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethenyl]benzene, nitrofen, β-endosulfan, 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethyl]benzene, 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane, bifenthrin, permethrin and fenvalerate) in vegetable and fruit samples. The effects of extraction time, extraction temperature, sample pH, stirring rate and desorption temperature on the extraction efficiency were investigated. Under the optimized conditions, the limits of detection for the eleven pesticides were in the range of 0.04-0.25μg/kg. The recoveries of the eleven pesticides in the vegetable and fruit samples were 81.5-111% with the relative standard deviations less than 11.2%.

Bioremediation of hexachlorocyclohexane (HCH) in soil using spent mushroom compost of Pleurotus ostreatus

Hexachlorocyclohexane (HCH), a highly chlorinated pesticide, was used worldwide in the 1950s and 1960s. HCH toxic residues are still detected in environmental compartments. Thus, effective, viable and eco-friendly strategy is required for its remediation. In this study, degradation of four HCH isomers was evaluated by amending contaminated soil using four treatments of spent mushroom compost (SMC) of Pleurotus ostraetus. The soil was incubated for 5 weeks and was sampled every seven days. Quantitative attenuation in HCH was calculated using gas chromatography–electron capture detector (GC-ECD) and metabolite was identified using gas chromatography–mass selective detector (GC-MSD). Maximum reduction 58%, 26%, 45%, and 64% for α-, β-, γ- and δ-HCH isomers, respectively, using SMC and soil (both unsterilized) showed that this treatment was the best for bioremediation of HCH in soil. However, when one of the factors, either soil or SMC, was sterilized, a significant reduction in HCH degradation was noticed. The second most reduction of isomers was seen during treatment where unsterilized SMC was added in sterilized soil followed by treatment where SMC was sterilized but soil was not. Abiotic control did not remove any significant quantities of HCH. Simple first-order (SFO) kinetic confirmed that SMC reduced the half-live manifolds as compared to biotic control. Only one metabolite δ-PCCH was identified during the course of study.

Optimization and comparison of membrane-protected micro-solid-phase extraction coupled with dispersive liquid-liquid microextraction for organochlorine pesticides using three different sorbents

A micro-solid-phase extraction technique has been developed, for determination of organochlorine pesticides in water media, using gas chromatography-electron capture detector. Response surface methodology was applied to optimize the performance of the extraction technique. Also, the effect of significant experimental parameters (i.e. extraction time, ionic strength, type and volume of the desorption solvent and desorption time) has been studied. Three frequently used solid sorbents; multi-walled carbon nanotube, silica-based C18, and polymeric solid sorbent (LiChrolut® EN), were implemented and independently optimized and the results were compared to find the best extraction setup. A dispersive liquid-liquid extraction procedure was also used to enhance the sensitivity of the method, showing enrichment factors of 14 to 40. The limits of detection of the optimized technique were less than 0.26 μg L−1 (for methoxychlor with C18) and RSD values were between 3.3 and 14.5% at 1 μg L−1. The calibration functions were linear up to 500 μg L−1 with R2 values of more than 0.995, for all sorbents. The figures of merit of the entire procedure showed that each of the studied sorbents could produce satisfactory results in ultra-trace determination organochlorine pesticides in water.

Detection of Organochlorine Pesticide (OCPs) Residues and Trace Metals in Some Selected Malt Drinks in Nigeria

In this study we evaluated the trace metals and toxic residues of pesticides in commercial malta drinks sold in Nigeria markets. Residual concentrations of seventeen (17) chlorinated hydrocarbons and trace metals were determined in fifteen samples of three batches each of five selected brands of Malta drink sold in Nigeria markets. Gas Chromatograph-Electron Capture Detector (GC-ECD) and Atomic Absorption Spectrophotometry (AAS) were employed in quantitative analysis. The results revealed that all the malt drink analyzed have one or more OCPs detected. The presence of eleven (11) OCPs residue were detected at varying concentrations. The total burden of OCPs in the samples was in the following order: AMS &gt; DUB &gt; MAG &gt; HIM &gt; MLT. Trace metals results revealed that Cd was below detection limit in all the samples while Pb; Ni and Cr were above World Health Organization and United State Environmental Protection Agency (WHO/USEPA) limits for drinking water.

Single-drop microextraction combined with gas chromatography-electron capture detection for the determination of acrylamide in food samples

A single-drop microextraction method followed by gas chromatography-electron capture detection was developed to determine acrylamide in food samples. Acrylamide was extracted by water and derivatized by hydrobromic acid in the presence of ammonium peroxydisulfate. The derivatization was carried out at 45 °C in 15 min using 46 µL of hydrobromic acid and 98 mg of ammonium peroxydisulfate. A 3.0-mL volume of the derivatized analyte was extracted using a 1.0-µL n-octanol droplet hanging from the needle tip of a GC microsyringe. After extraction, the extract was injected into the gas chromatograph. The influence of experimental parameters effective on derivatization reaction yield and extraction performance was studied. The limit of detection and quantification, relative standard deviation and linearity of the method were 0.60 µg/L, 2.0 µg/L, <6.0%, and 2.0–100.0 µg/L, respectively. The method was utilized to determine acrylamide in three food samples (i.e., bread, potato chips and cookie).

Comparative Screening Analytic Methods for Elderly of Blood Methylmercury Concentration between Two Analytical Institutions

Methylmercury is widely known to be a toxic substance in the human, especially a nervous system. However, it is difficult to accurately measure the amount of methylmercury in blood, and the form of methylmercury is variously presented. The purpose of study was to compare the total mercury and methylmercury measurements techniques and detection levels between analytical institutions in two countries using the same elderly human blood samples. Total mercury using gold amalgamation direct mercury analysis method (both) and methylmercury using the dithizone extraction and gas chromatography-electron capture detector (GC-ECD) method (N Lab in Japan) and the cold vapor atomic fluorescence spectrophotometer (CVAFS) method (D Lab in Korea) were measured in 47 subjects who agreed to participate in this study. Total mercury concentrations in both analytical laboratories were observed at similar levels (9.4 versus 9.5 ug/kg, p=0.898) and the distribution was highly correlated. However, the concentration of methylmercury showed some difference between two laboratories (9.1 versus 8.6 ug/kg, p<0.001). Due to different recovery rates by different analytical methods, it is assumed that the methyl/total mercury ratio in N lab in Japan was higher than D lab in Korea (96.8 versus 90.4%, p<0.001). The GC-ECD was more sensitive method than CVAFS in methylmercury analytic techniques.

Organochlorine pesticides in two fish species from the southern Caspian Sea

In the present research, we aimed to investigate organochlorine toxins accumulated in both Rutilus frisii kutum and Liza aurata captured at the southern Caspian Sea. At six sampling stations, organochlorine toxins were measured in fish tissues by the gas chromatography–electron capture detector (GC-ECD) method. Total organochlorine toxins ranged from 2.102 ppb to 9.033 ppb in L. aurata at the study area. The highest content of total organochlorine toxins was obtained at station 5, whereas the lowest content was achieved at station 4.In L. aurata, lindane showed the highest level among the measured components (1.642 ppb), whereas α-lindane showed the highest mean level of the measured components (0.57 ppb). In this investigation, the total amount of organochlorine compounds in R. frisii kutum was more than that in L. aurata, but these compounds indicated no significant difference between the two types of fishes (p > 0.05). Moreover, the measured components in both types of fishes were lesser than the allowable limit.

Fate, distribution, and bioconcentration of pesticides impact on the organic farms of Cameron Highlands, Malaysia.

Occurrence and distribution of organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), and pyrethroid pesticides (PYRs) residues in the leafy vegetables were analyzed together with the soil samples using gas chromatography-electron capture detector. Edible tissues of vegetables showed detectable residues of these compounds indicating the influence of the conventional farms and nearby organic farms. In the vegetables, the OCPs concentrations were recorded as nd-133.3ng/g, OPPs as nd-200ng/g, and PYRs as nd-33.3ng/g. In the soil, the OCPs concentrations were recorded as nd-30.6ng/g, OPPs as nd-26.6ng/g, and for PYRs as nd-6.7ng/g. Bioconcentration factor (BCF) was higher for the OPPs (0.3) than the OCPs and PYRs (1.1). The OCPs concentration in the vegetables decreased in the following order: spinach > celery > broccoli > cauliflower > cabbage > lettuce > mustard. For OPPs, the concentration decreased in the following order: cauliflower > spinach > celery > cabbage > broccoli > lettuce > mustard and for PYRs as spinach > celery > lettuce > cabbage > broccoli. Principal component analysis indicates that the sources of these pesticides are not the same, and the pesticide application on the vegetables depends on the type of crop. There is a significant positive correlation between OPPs and the soil (r = 0.65) as compared to OCPs and PYRs (r = 0.1) as the vegetables accumulated OPPs more efficiently than OCPs and PYRs.