Multiresidue Pesticide Research Articles

Optimization of multi-residue method for targeted screening and quantitation of 243 pesticide residues in cardamom (Elettaria cardamomum) by gas chromatography tandem mass spectrometry (GC-MS/MS) analysis

Higher matrix interference makes the multi-residue pesticide analysis in spices more challenging. A simple, sensitive, and robust large-scale multi-residue method was developed for the rapid analysis of 243 pesticides in cardamom matrix by gas chromatography tandem mass spectrometry (GC-MS/MS). Prehydration of cardamom in 1:4 sample:water for 30 min improved the homogeneity and extractability. QuEChERS extraction followed by cleanup with 25 mg primary secondary amine, 100 mg C18, and 10 mg graphitized carbon black to 1 ml supernatant was used for sample preparation. Reconstitution of final extract in ethyl acetate reduced matrix co-extract up to 60%. The method was validated according to the SANTE/11,945/2015 guidelines. The limit of quantification was ≤0.01 mg kg−1, and the recovery was within 70.0–120.0%, with ≤20% RSD for the majority of pesticides. The method was used for screening market samples, and the detected residues were devoid of any risk of acute toxicity related to dietary exposure.

Evaluation of organochlorine and organophosphorus pesticides residues in the sediment and muscles of Nile tilapia Oreochromis niloticus (Linnaeus, 1758) fish from a River Nile Canal, Egypt

The paper reports the levels of multi-pesticide residues in the sediment and fish (Oreochromis niloticus) muscle collected from Bahr Shebeen Canal (BSC), a River Nile Canal, from September 2014 to December 2015. Samples were analysed using capillary GC chromatography, and average pesticide residue concentrations were determined. The results indicated the presence of different types of organophosphorus (OPPs) and organochlorine (OCPs) pesticides in varying degrees. Both types of residue in the sediment samples were higher than in fish muscle. The spatial and seasonal variations of OPPs and OCPs levels in sediment and fish muscle are discussed. It was found that these levels were higher than those detected from other Egyptian localities and also higher than the international permissible limits. Therefore, it is recommended to monitor the pesticide residues continuously in this, and similar, water resources to ensure the protection of the aquatic food resources.

Currently and recently used pesticides in Central European arable soils

Although large amounts of pesticides are used annually and a majority enters the soil to form short- or long-term residues, extensive soil surveys for currently used pesticides (CUPs) are scarce. To determine the status of CUPs' occurrence in arable land in Central Europe, 51 CUPs and 9 transformation products (TPs) were analysed in 75 arable soils in the Czech Republic (CR) several months after the last pesticide application. Moreover, two banned triazines (simazine and atrazine) and their TPs were analysed because of their frequent detection in CR waters. Multi-residue pesticide analysis on LC-MS/MS after soil QuEChERS extraction was used. The soils contained multiple pesticide residues frequently (e.g. 51% soils with ≥5 pesticides). The levels were also noticeable (e.g. 36% soils with ≥3 pesticides exceeding the threshold of 0.01mg/kg). After triazine herbicides (89% soils), conazole fungicides showed the second most frequent occurrence (73% soils) and also high levels (53% soils with total conazoles above 0.01mg/kg). Frequent occurrence was found also for chloroacetanilide TPs (25% of soils), fenpropidin (20%) and diflufenican (17%). With the exception of triazines' negative correlation to soil pH, no clear relationships were found between pesticide occurrence and soil properties. Association of simazine TPs with terbuthylazine and its target crops proved the frequent residues of this banned compound originate from terbuthylazine impurities. In contrast, frequent atrazine-2-hydroxy residue is probably a legacy of high atrazine usage in the past. The occurrence and levels of compounds were closely associated with their solubility, hydrophobicity and half-life. The results showed links to CR water-monitoring findings. This study represents the first extensive survey of multiple pesticide residues in Central European arable soils, including an insight into their relationships to site and pesticide properties.

Statistical Analysis for Quality Adjustment of the Analytical Curve for Determination of Pesticide Multiresidue in Pineapple Samples

This work describes the development of an analytical methodology based on the modified QuEChERS method and GC/MS detection involving the analysis of 38 pesticides in pineapple from a local market in Fortaleza-Brazil. Matrix-standard calibration and heteroscedasticity have been studied by a weighted least squares linear regression model application. The analytical curves for most of the analytes (except cyproconazole and pyraclostrobin) presented heteroscedasticity by weighted least square regression (WLS). The weighted correlation coefficient values were in the range of 0.9690 to 0.9987 (linear range of 0.03 to 0.50 mg kg−1). The calibration curves obtained by applying regression by ordinary least squares (OLS) showed relative errors of approximately 32.3% for fenpropathrin, 23.1% for buprofezin, 17.4% for methyl parathion, and 13.9% for ametryn. Analysis of commercial pineapple samples revealed the presence of methyl parathion, buprofezin, ametryn, and fenpropathrin at 0.023 ± 0.0037, 0.013 ± 0.0047, 0.043 ± 0.0156, and 0.031 ± 0.0049 mg kg−1, respectively.

Simultaneous liquid chromatography/mass spectrometry determination of both polar and “multiresidue” pesticides in food using parallel hydrophilic interaction/reversed-phase liquid chromatography and a hybrid sample preparation approach

Pesticide testing of foodstuffs is usually accomplished with generic wide-scope multi-residue methods based on liquid chromatography tandem mass spectrometry (LC–MS/MS). However, this approach does not cover some special pesticides, the so called “single-residue method” compounds, that are hardly compatible with standard reversed-phase (RP) separations due to their specific properties. In this article, we propose a comprehensive strategy for the integration of single residue method compounds and standard multiresidue pesticides within a single run. It is based on the use of a parallel LC column assembly with two different LC gradients performing orthogonal hydrophilic interaction chromatography (HILIC) and reversed-phase (RPLC) chromatography within one analytical run. Two sample aliquots were simultaneously injected on each column, using different gradients, being the eluents merged post-column prior to mass spectrometry detection. The approach was tested with 41 multiclass pesticides covering a wide range of physicochemical properties across several orders of log Kow (from −4 to +5.5). With this assembly, distinct separation from the void was attained for all the pesticides studied, keeping similar performance in terms of sensitivity, peak area reproducibility (<6 RSD% in most cases) and retention time stability of standard single column approaches (better than±0.1min). The application of the proposed approach using parallel HILIC/RPLC and RPLC/aqueous normal phase (Obelisc) were assessed in leek using LC–MS/MS. For this purpose, a hybrid QuEChERS (Quick, easy, cheap, effective, rugged and safe)/QuPPe (quick method for polar pesticides) method was evaluated based on solvent extraction with MeOH and acetonitrile followed by dispersive solid-phase extraction, delivering appropriate recoveries for most of the pesticides included in the study within the log Kow in the range from −4 to +5.5. The proposed strategy may be extended to other fields such as sport drug testing or environmental analysis, where the same type of variety of analytes featuring poor retention within a single chromatographic separation occurs.

Sensitivity enhancement using a microbore column and pulsed pressure injection in the simultaneous analysis of 356 pesticide multiresidues by gas chromatography–tandem mass spectrometry

For more rapid and sensitive simultaneous analysis of a 356 pesticide multiresidues by gas chromatography–tandem mass spectrometry (GC–MS/MS), a microbore (20 m length × 0.18 mm i.d.) column, instead of the conventional narrow bore column (30 m length × 0.25 mm i.d.), and pulsed pressure injection (PPI) were evaluated in this study. An analysis time of 35.2 min with the narrow bore column was greatly reduced to 17.8 min with the microbore column. Retention times of all target compounds on the new microbore column were adjusted using the automated adjustment of retention time function. The microbore column gave significantly higher peak heights and narrower peak widths compared with the narrow bore column, resulting in enhanced sensitivity. The use of PPI at an optimized pressure of 250 kPa for the microbore column also increased peak heights and signal-to-noise (S/N) ratio by about 30%, indicating more than twofold–threefold enhancement of sensitivity compared with the narrow bore column without PPI. In the best case of the late eluting compound etofenprox, the S/N ratio significantly increased more than ninefold. In conclusion, compared to a narrow bore column, using a microbore analytical column with PPI function produced peak sensitivity enhancement and a shorter analysis time.

An efficient cleanup method coupled with gas chromatography and mass spectrometry for multi-pesticides residue analysis in complex plant matrices.

We aimed to develop an efficient cleanup method for multi-pesticides residue analysis in complex plant matrices, shallot, ginger, garlic, onion, leek, and celery. Column chromatography was used as the cleanup method and fabricated with florisil and graphitized carbon black as the adsorbents. The amount of the graphitized carbon black adsorbent and the choice of the elution solvent were systematically investigated for exploring the best combination. The target pesticides covered organochlorine, pyrethroid, and organophosphorus pesticides, and were 38 in total. The method validation and comparison were performed to verify its feasibility and advantages in operation convenience and purification efficiency. The method limit of quantitation varied from 0.01 to 0.03mg/kg, which depends on the pesticides and the sample matrices. The recoveries of the pesticides ranged from 60.5 to 128% (RSD≤19.0%) at the spiked concentration level of 0.01 (or 0.03) mg/kg and 62.9 to 130% (RSD≤13.0%) at 0.1mg/kg. Compared with the commercial cleanup solid-phase extraction cartridges, the present adsorbent combination displayed better purification effect and shorter sample pretreatment time, demonstrating potential application prospect in the complex matrix sample analysis.

Authenticity testing of environment-friendly Korean rice (Oryza sativa L.) using carbon and nitrogen stable isotope ratio analysis

The increasing demand for organic foods creates, in turn, a pressing need for the development of more accurate tools for the authentication of organic food in order to ensure both fair trade and food safety. This study examines the feasibility of δ13C and δ15N analyses as potential tools for authentication of environment-friendly rice sold in Korea. δ13C and δ15N examination in different rice grains showed that environment-friendly rice can be successfully distinguished from conventional rice. No multi-residue pesticides were detected in the examined rice samples, including conventional rice. This study demonstrates the complementary feasibility of δ13C and δ15N analyses for the authentication of environment-friendly rice sold in Korea in cases where pesticide residue analysis alone is insufficient for discrimination of organic and conventional rice. In future, complementary analyses including compound-specific isotope ratio analysis might be employed for improving the reliability of organic authentication.

A Rapid Method for the Quantitative Determination of 34 Pesticides in Nonalcoholic Carbonated Beverages Using Liquid-Liquid Extraction Coupled to Dispersive Solid-Phase Cleanup Followed by Gas Chromatography with Tandem Mass Spectrometry.

An economical, rapid, and sensitive multiresidue method using liquid-liquid extraction (LLE) coupled with dispersive SPE (dSPE) cleanup was developed for the quantitative determination of 34 multiclass multiresidue (MCMR) pesticides (14 organochlorines, eight organophosphates, 10 synthetic pyrethroids, and two herbicides) in nonalcoholic carbonated beverages (cola, orange, lemon-lime, and citra) using GC with tandem MS. The procedure mainly involved LLE by dichloromethane and dSPE cleanup in the presence of magnesium sulfate, primary secondary amine, and C18. The RSD of the developed method was found to be less than 14%. The LOD and LOQ values for all the analyzed pesticides were found in the ranges of 0.001-0.027 μg/L and 0.004-0.088 μg/L, respectively. The LOQ levels of the pesticides analyzed were found to be well below the recommended limit by the European Union (0.1 μg/L in water). The mean recoveries of pesticides in different nonalcoholic carbonated beverages (cola, orange, lemon-lime, and citra) were found to be in the range of 79-111%, with RSDs less than 11%. The validation data prove that the method can be acceptable to regulatory agencies for the routine analysis of MCMR pesticides in nonalcoholic carbonated beverages.

Detection of Organophosphorus Pesticide Residues in Leaf Lettuce and Cucumber Through Molecularly Imprinted Solid-Phase Extraction Coupled to Gas Chromatography

How to determine multipesticide residues in vegetables is important for the modern society. The development of a simple, rapid, and sensitive method to determine pesticide residues is significant. Our study used common vegetables—leaf lettuce and cucumber, and a new molecularly imprinted polymer (MIP) was synthesized using O,O′-dimethylthiophosphoryl chloride, an intermediate for the manufacture of organophosphorus pesticides, as the template, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The adsorption capacities of the prepared MIP toward five organophosphorus pesticides (trichlorfon, dichlorvos, dimethoate, imidacloprid, and methamidophos) were evaluated, and its potential as a sorbent for solid-phase extraction was investigated. A novel method for the simultaneous determination of multiple organophosphorus pesticide residues in vegetables was developed by utilizing molecularly imprinted solid-phase extraction (MISPE) coupled with gas chromatography. Under optimal solid-phase extraction conditions, with a flow rate of 3.0 mL/min for loading 100 mL, the enrichment factor was in the range of 36–452 for the five organophosphorus pesticides. The peak area precision of the five organophosphorus pesticides based on five replicates was from 1.59 to 4.07%. The leaf lettuce spiked sample was used to verify the fortified recovery for this method, and the results ranged from 87.48 to 97.85%. The MISPE–gas chromatography method could be used to detect organophosphorus pesticide residues in lettuce leaf and cucumber from the farmer’s market, and the detection limit had no obvious difference from the national standards. This method can meet the requirements of the analysis of pesticides in complex matrix.

Evaluation of membrane filtration for cleanup in multi-residue pesticide analysis of spinach

This study reports a new membrane filtration-based cleanup method for the analysis of pesticides. Recovery and cleanup by membrane filtration using 11 different membranes, classified by their molecular weight cut-off, pore size, and material, were examined. Three different eluent mixtures were also examined. The results indicated that membranes with a 0.1-μm pore size were the most effective among those tested. In particular, hydrophobic polyvinylidene difluoride and hydrophobic polytetrafluoroethylene gave better recoveries and cleanup than other membranes. Results from GC chromatograms and matrix effects showed that membrane filtration afforded better cleanup than the modified QuEChERS method. Furthermore, over 90% of the 89 pesticides tested had acceptable recoveries using these two membranes, according to an acceptable recovery range of 70–120%. Therefore, this technique has potential as an effective cleanup method.

Multi-pesticides residue analysis of grains using modified magnetic nanoparticle adsorbent for facile and efficient cleanup.

A facile, rapid sample pretreatment method was developed based on magnetic nanoparticles for multi-pesticides residue analysis of grains. Magnetite (Fe3O4) nanoparticles modified with 3-(N,N-diethylamino)propyltrimethoxysilane (Fe3O4-PSA) and commercial C18 were selected as the cleanup adsorbents to remove the target interferences of the matrix, such as fatty acids and non-polar compounds. Rice was used as the representative grain sample for method optimization. The amount of Fe3O4-PSA and C18 were systematically investigated for selecting the suitable purification conditions, and the simultaneous determination of 50 pesticides and 8 related metabolites in rice was established by liquid chromatography-tandem mass spectrometry. Under the optimal conditions, the method validation was performed including linearity, sensitivity, matrix effect, recovery and precision, which all satisfy the requirement for pesticides residue analysis. Compared to the conventional QuEChERS method with non-magnetic material as cleanup adsorbent, the present method can save 30% of the pretreatment time, giving the high throughput analysis possible.

Evaluation of the matrix-like effect in multiresidue pesticide analysis by gas chromatography with tandem mass spectrometry.

In multiresidue pesticide analysis using gas chromatography, it has long been recognized that an increase in the number of pesticides present in a standard solution can result in an enhancement of the peak responses of certain pesticides. Despite being widely acknowledged, this phenomenon has been rarely studied and is poorly understood. In this study, the authors have tentatively called this phenomenon the "matrix-like effect" and demonstrated it clearly using gas chromatography with tandem mass spectrometry. Five selected pesticides, namely, omethoate, terbufos, malathion, procymidone, and permethrin, and four internal standard candidates, namely, triphenyl phosphate, naphthalene-d8 , phenanthrene-d10 , and fluoranthene-d10 , were used to evaluate the matrix-like effect following the addition of 58, 108, and 166 other pesticides. With the exception of naphthalene-d8 , the responses of all evaluated pesticides and internal standard candidates were dramatically enhanced by the addition of up to 166 coexisting pesticides. The relative response factors of the five pesticides to each internal standard candidate were not constant under the conditions studied, meaning that these internal standard candidates did not adequately compensate for the matrix-like effect, at least for the five evaluated pesticides. The results revealed that the presence of various mixtures of pesticides in standard solutions might act as an unintentional analyte protectant, that is, some sort of troublesome "quasi-matrix."

Evaluation of Some Pesticide Residues in Fruits import by High Performance Liquid Chromatography

Pesticide residues have been found in various fruits and vegetables. This study collected 24 samples and reported a method based on High Performance Liquid Chromatography (HPLC). For determination of pesticide residues used in Some fruits which were collected from different markets of Baghdad city to make) 24) samples from (peel , core, mixture) for each type of fruits markets as: Oranges( Egypt , Africa), Pomegranate ( Egypt), Mango ( Kenya ), Pears (China), Plum fruits ( Africa ) , Kiwi (Turkey ) .That detective of ( 5 ) different pesticides (diazinon, malathion, chlorpyrifos ,parathion and cypermethrin). The results were detected of multi-residues of pesticides on the fruit in ( peel , core , mixture ) may be in the limit of Maximum residue limits(MRL) or higher of it . The pesticides detected that exceeding the limits are: cypermethrin in Kiwi (peel, core and mixture)at(0.204,0.038, 0.537), in pomegranate detected in (peel and mixture) at (0.509,0.189) mg/kg , Diazinon detccted in Egyptian orange in (peel ,core and mixture) at (0.031,0.207, 0.099) mg/kg . Malathion and Parathion was not detected at any type of fruits and that results was compared with codex of FAO/WHO(2013). That data is important to monitor residues in food and to fill gaps in current knowledge would be helpful in assessing human exposure risks from ingestion of contaminated Fruits Imported to our country.

Evaluation of Some Pesticide Residues in Fruits import by High Performance Liquid Chromatography

Pesticide residues have been found in various fruits and vegetables. This studycollected 24 samples and reported a method based on High Performance Liquid Chromatography (HPLC). For determination of pesticide residues used in Some fruits which were collected from different markets of Baghdad city to make) 24) samples from (peel , core, mixture) for each type of fruits markets as: Oranges( Egypt , Africa), Pomegranate ( Egypt), Mango ( Kenya ), Pears (China), Plum fruits ( Africa ) , Kiwi (Turkey ) .That detective of ( 5 ) different pesticides (diazinon, malathion, chlorpyrifos ,parathion and cypermethrin). The results were detected of multi-residues of pesticides on the fruit in ( peel , core , mixture ) may be in the limit of Maximum residue limits(MRL) or higher of it . The pesticides detected that exceeding the limits are: cypermethrin in Kiwi (peel, core and mixture)at(0.204,0.038, 0.537), in pomegranate detected in (peel and mixture) at (0.509,0.189) mg/kg , Diazinondetccted in Egyptian orange in (peel ,core and mixture) at (0.031,0.207, 0.099) mg/kg . Malathion and Parathion was not detected at any type of fruits and that results was compared with codex of FAO/WHO(2013). That data is important to monitor residues in food and to fill gaps in current knowledge would be helpful in assessing human exposure risks from ingestion of contaminated Fruits Imported to our country.

Influence of QuEChERS modifications on recovery and matrix effect during the multi-residue pesticide analysis in soil by GC/MS/MS and GC/ECD/NPD

A QuEChERS extraction followed by GC/MS/MS and GC-μECD/NPD for 216 pesticide and metabolites determination in soil simultaneously were developed and compared. Volume of water, volume and polarity of solvent, and cleanup sorbents (C18, GCB, PSA) were optimized. The QuEChERS with and without purification step were applied to estimate effectiveness of the method. The recovery and matrix effect (ME) were critical parameters within each tested procedure. The optimal method without cleanup was validated. Accuracy (expressed as recovery), precision (expressed as RSD), linearity, LOQ, and uncertainty were determined. The recoveries at the three spiking levels using matrix-matched standards ranged between 65 and 116% with RSD ≤17 and 60–112% with RSD ≤18% for MS/MS and μEC/NP, respectively. The LOQ ranged from 0.005–0.01 mg/kg for MS/MS to 0.05 mg/kg for μEC/NP. The ME for most of pesticides resulted in enhancement of the signal and depended on the analyte and detection system: MS/MS showed ME from −25 to 74%, while μEC/NP from −45 to 96%. A principal component analysis was performed to explain the relationships between physicochemical parameters and ME of 216 pesticides. The QuEChERS protocol without the cleanup step is a promising option to make the method less expensive and faster. This methodology was applied in routine analysis of 263 soil samples in which p,p’ DDT was the most frequently detected (23.5% of samples) and pendimethalin with the highest concentration (1.63 mg/kg).

Salting-out Assisted Liquid-Liquid Extraction for the Determination of Multiresidue Pesticides in Alcoholic Beverages by High Performance Liquid Chromatography

A salting-out assisted liquid-liquid extraction (SALLE) method followed by high-performance liquid chromatography with ultraviolet-visible detector (HPLC-UV/Vis) has been proposed for determination of five multiclass pesticides residues including, atrazine, ametryn, terbutryn, carbaryl and chlorothalonil from various alcoholic beverages: beer, wine and Ethiopian honey wine (<i>Tej</i>). Experimental parameters influencing the extraction efficiency of the method such as the type and concentration of salt, volume of acetonitrile (the extraction solvent) and pH of the sample were assayed and the optimum conditions were established. Under the optimum experimental conditions, matrix-matched calibration curves were constructed using beer sample as the representative matrix and good linearity over wide concentration ranges were obtained with coefficient of determination (r²) of 0.997 or better. The limits of detection (LOD) and quantification (LOQ) of the method, which were determined as 3 and 10 times a signal-to-noise ratio (S/N), were in the ranges of 1.3-3.9 and 4.5–12.8 μg L^-1, respectively. Precisions studied in terms of repeatability and intermediate precision (with-in lab reproducibility) at two concentration levels have demonstrated acceptable %RSD values, which were less than 10% in both cases. The applicability of the method was also investigated by analyzing various alcoholic beverages and demonstrated satisfactory recoveries in the ranges of 71-104% with their corresponding %RSDs less than 10% in all cases. The results of the study revealed that the developed SALLE method is selective and efficient sample preparation procedure prior to quantitative analysis of the target analytes by HPLC-UV/Vis.

Comparative Evaluation of Extraction Procedures and Chromatographic Techniques for Analysis of Multiresidue Pesticides in Honey

Comparative Evaluation of Extraction Procedures and Chromatographic Techniques for Analysis of Multiresidue Pesticides in Honey

Fractional factorial design based microwave-assisted extraction for the determination of organophosphorus and organochlorine residues in tobacco by using gas chromatography-mass spectrometry.

Sample preparation is often the main bottleneck in analyzing biological samples. Particularly, effective evaluation of sample preparation conditions usually involves multiple factors and tedious and time-consuming experiments. In this study, fractional factorial design, specifically orthogonal array testing, was employed to screen and optimize multiple extraction parameters in concise but representative experiments. An efficient and sensitive method was developed to determine organophosphorus and organochlorine pesticide residues in tobacco, via microwave-assisted extraction and gas chromatography coupled with mass spectrometry detection. With orthogonal array design, screening, and optimization tests were subsequently conducted to determine the range, impact rank, and possible interactions of extraction temperature, time, microwave power, additive salt, and additive water. Orthogonal array testing selectively reduces the size and cost of experiments and meanwhile provides more information compared to the traditional experimental design that optimizes one factor at a time. A good linear range (0.02-2.00 μg/mL), limits of detection (0.001-0.098 μg/mL), and recovery rates (70.4-107.1%) were demonstrated by spiking known concentrations of multiple pesticide standards in tobacco samples. The established method was then successfully applied to the determination of multipesticide residues in raw tobacco leaves and commercial cigarettes.

Monitoring and distribution patterns of pesticide residues in soil from cotton/wheat fields of Pakistan.

The excessive use of hazardous pesticides for massive cotton and wheat production has deteriorated the quality of Okara district's soil. Thus, in order to sustain the production of good-quality food, it is essential to determine the residue levels of pesticides in the agricultural soil and define their possible sources. Thus, the present study focused on the determination of selected pesticides in the soil samples obtained from cotton/wheat fields by using the modified multi-residue pesticide analysis method based on GCMS and HPLC-UV. Most of soil samples were found to be highly contaminated with imidacloprid, chlorpyrifos, and α-cypermethrin residues. Selected pesticides were significantly correlated with each other at p<0.05 except imidacloprid, which was negatively correlated with triazophos, MCPA methyl ester, selected pyrethroid pesticides, and their metabolite. Soil pH and phosphate levels were significantly positively correlated while sulfate content was negatively correlated with most of selected pesticides. The varimax normalized factor analysis divides the selected pesticides to the two major factors that explained 87.19% of the total variance which evidenced that pesticide in the same cluster shared a common source in the soil. A significant negative correlation of chlorpyrifos in the second factor pointed towards a source different from other pesticides. Factor and cluster analysis indicated that sulfate levels of soil positively affected the persistence/ mobility of imidacloprid.