Chlorpyrifos Methyl Research Articles

Determination of 28 pesticides applied on two tomato cultivars with a different surface/weight ratio of the berries, using a multiresidue GC-MS/MS method

The behavior of 28 pesticides on two tomato cultivars with a different surface/weight (S/W) ratio of the berries (S/W, Birikino vs. Tombola) was studied, in order to provide appropriate indications about their persistence on crops reaching the pre-harvest interval (PHI). Quantitative analysis was performed using a GC MS/MS method. Birikino cv. (BIR) was a “cherry type tomato” with a double S/W ratio compared with Tombola cv. (TOM). The results showed a different pesticide behavior. Azoxystrobin, Boscalid, Bupirimate, Difenoconazole, Etofenprox, Iprodione, Mepanipyrim, Myclobutanil, Tebuconazole, Zoxamide, Metalaxyl M, Pyrimethanil, Tetraconazole, Benalaxyl, Cyprodinil, Fenamidone, Famoxadone and Fludioxonil immediately after treatments showed residues on BIR higher than TOM, and this behavior is consistent with its greater exposed surface. BIR showed higher decay rates of these pesticides during the whole trial, nevertheless residue averages remained higher than TOM reaching the time of harvest. Residues at the PHI were all below their Maximum Residue Levels (MRLs), but data indicated that they could exceed their legal limits especially if the above-mentioned active ingredients were employed more than once per crop cycle on cherry type tomatoes. As regards to Chlorpyrifos, Chlorpyrifos methyl, Triadimenol, Pyridaben and Tebufenpyrad, no different residual behavior related to S/W ratio of the cultivars was observed. Even in this case, residues at the PHI were all below MRLs. As for Cyfluthrin, Deltamethrin, Lambda cyhalothrin, Etoxazole and Cyproconazole, residues were lower than the limit of quantitation (LOQ) of the analytical method just after the treatment, according to their low doses of employment.

HPLC-MS/MS method for the measurement of insecticide degradates in baby food.

A solid phase extraction method was developed to isolate four insecticide degradates from baby food that were measured subsequently using high-performance liquid chromatography–tandem mass spectrometry. The degradates [parent insecticide] measured were malathion dicarboxylic acid [malathion], 3,5,6-trichloro-2-pyridinol [chlorpyrifos, chlorpyrifos methyl] (TCPy), cis/trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid [permethrin, cypermethrin, cyfluthrin], and 3-phenoxybenzoic acid [general pyrethroid]. All degradates produced recoveries between 80 and 120% except TCPy in fruit (122% recovery), and all relative standard deviations were <16%. Use of this method demonstrated that insecticide degradates were found in baby foods frequently purchased in the United States, supporting the need for this method. These data will assist in differentiating whether biomarker levels of insecticide metabolites are the result of exposures to the toxic insecticide or its preformed degradate.

Pesticide residues in grain from Kazakhstan and potential health risks associated with exposure to detected pesticides

This paper presents the first study of pesticide residue results in grain from Kazakhstan. A total of 80 samples: barley, oat, rye, and wheat were collected and tested in the accredited laboratory. Among 180 pesticides, 10 active substances were detected. Banned pesticides, such as DDTs, γ-HCH, aldrin and diazinon were found in cereal grain. Chlorpyrifos methyl and pirimiphos methyl were the most frequently detected residues. No residues were found in 77.5% of the samples, 13.75% contained pesticide residues at or below MRLs, and 8.75% above MRLs. The greatest percentage of samples with residues (29%) was noted for wheat, and the lowest for rye (20%). Obtained data were used to estimate potential health risks associated with exposure to these pesticides. The highest estimated daily intakes (EDIs) were as follows: 789% of the ADI for aldrin (wheat) and 49.8% of the ADI for pirimiphos methyl (wheat and rye). The acute risk from aldrin and tebuconazole in wheat was 315.9% and 98.7% ARfD, respectively. The results show that despite the highest EDIs of pesticide residues in cereals, the current situation could not be considered a serious public health problem. Nevertheless, an investigation into continuous monitoring of pesticide residues in grain is recommended.

Implementing the contamination prevention programs in the pesticide industry by infrared spectroscopy

An infrared spectroscopy based methodology has been successfully developed to implement contamination prevention programs in the pesticide industry. Sensitivity of the IR procedure, traditionally considered the Achilles Hell of the technique, has been improved by using a transmission cell with an open upper side, an internal volume of 35 µL and an optical pathlength of 0.5mm, providing detection limits of 32 mg L(-1) for folpet and 48 mg L(-1) for cymoxanil. The manufacturing of folpet and cymoxanil was employed as an example and the IR methodology was validated for the implementation of contamination prevention programs in the pesticide industry. The swab test and rinsate method were employed as sampling methods and results obtained by both were compared and correlated. Samples were analyzed from a qualitative and quantitative point of view. Qualitative information can be obtained by comparing the sample spectra with those of a new IR spectral library with approximately 50 entries of pesticide standards. Positive identification of folpet in all the analyzed samples was obtained. Other pesticides present in swab and rinsate samples positively identified by IR and confirmed by gas chromatography-mass spectrometry (GC-MS), were metalaxyl and chlorpyrifos methyl used in the manufacture of previous formulations. The amount of folpet in the swab and rinsate samples obtained by the developed IR method was compared with those of a reference procedure, being statistically comparable.

Simultaneous Detection of Fenitrothion and Chlorpyrifos-Methyl with a Photonic Suspension Array

A technique was developed for simultaneous detection of fenitrothion (FNT) and chlorpyrifos-methyl (CLT) using a photonic suspension array based on silica colloidal crystal beads (SCCBs). The SCCBs were encoded with the characteristic reflection peak originating from the stop-band of colloidal crystal. This approach avoids the bleaching, fading or potential interference seen when encoding by fluorescence. SCCBs with a nanopatterned surface had increased biomolecule binding capacity and improved stability. Under optimal conditions, the proposed suspension array allowed simultaneous detection of the selected pesticides in the ranges of 0.25 to 1024 ng/mL and 0.40 to 735.37 ng/mL, with the limits of detection (LODs) of 0.25 and 0.40 ng/mL, respectively. The suspension array was specific and had no significant cross-reactivity with other chemicals. The mean recoveries in tests in which samples were spiked with target standards were 82.35% to 109.90% with a standard deviation within 9.93% for CLT and 81.64% to 108.10% with a standard deviation within 8.82% for FNT. The proposed method shows a potentially powerful capability for fast quantitative analysis of pesticide residues.

Determination and risk assessment of pesticide residues in lake Amvrakia (W. Greece) after agricultural land use changes in the lake's drainage basin

A monitoring study of pesticides belonging to different chemical families was carried out in Amvrakia lake (West Greece) waters after land use changes in the lake's basin. Based on land-use patterns, nine sampling points were selected. Pesticides were extracted by solid phase extraction (SPE) using Oasis HLB cartridges and analysed by gas chromatographic techniques with flame thermionic and mass-spectra detection. Pesticides detected during the monitoring survey include eight herbicides (alachlor, atrazine, s-metolachlor, pendimethalin, prometryne, propachlor, simazine, trifluralin) and one metabolite (deethyl atrazine) with concentration levels up to 807 ng L−1 (recorded for alachlor), eight insecticides (azinphos methyl, chlorpyrifos, chlorpyrifos methyl, diazinon, dimethoate, fenitrothion, malathion, methidathion) with concentration levels up to 490 ng L−1 (recorded for azinphos methyl) and six fungicides (benalaxyl, cyproconazole, fenarimol, pyrimethanil, triadimefon, triadimenol) with concentration levels up to 408 ng L−1 (recorded for pyrimethanil). More frequently detected pesticides were atrazine, deethyl atrazine, alachlor, azinphos methyl, chlorpyrifos methyl, diazinon and pyrimethanil. The higher concentrations were measured during spring-early summer period, following seasonal application of pesticides and diminished significantly during winter. Littoral sampling stations presented higher pesticide concentration levels and more frequent detection. Aquatic risk assessment was based on the Risk Quotient (RQ = MEC/PNEC) deterministic method regarding three trophic levels: algae, aquatic invertebrates and fish. Non-acceptable risk for 10 compounds was observed when maximum concentrations were used. Compliance to EC environmental quality standards is also discussed.

Washing effects of limonene on pesticide residues in green peppers

The presence of pesticide residues in food has caused much concern. The low health risks and environmental impacts of limonene make it a very interesting solvent for use in green chemistry. Washing effects of limonene on pesticide residues of methyl chlorpyrifos, chlorothalonil, chlorpyrifos, fenpropathrin and deltamethrin were investigated in green pepper. Results showed that washing with a low concentration of limonene for 5 min (where LOQ is limit of quantitation) caused 53.67%, <LOQ, 64.29%, 68.69% and 66.22% loss of the above pesticides, respectively, while corresponding values of washing with a high concentration were 84.64%, <LOQ, 90.46%, 89.00% and 89.36%, respectively. Washing with a low concentration of limonene for 10 min produced 55.90%, <LOQ, 66.19%, 72.08% and 73.25% loss, respectively, while corresponding values of washing with a high concentration were 94.42%, <LOQ, 96.58%, 92.04% and < LOQ, respectively. The reductions due to washing with tap water (for 10 min) and the emulsion with only egg yolk lecithin (at high concentration for 10 min) were 25.18 %, 37.83%, 21.84%, 20.87%, 13.86% and < LOQ, 59.70%, 54.09%, 54.76%, 54.47%, respectively. The data indicated that washing with a low concentration of limonene for 5 min was the optimal treatment for elimination of pesticide residues in green pepper, considering effect and treatment time as well as cost.

Efficacy of a Mosaic Long-Lasting Insecticide Net, PermaNet 3.0, against Wild Populations ofCulex quinquefasciatusin Experimental Huts in Togo

PermaNet 3.0 was evaluated againstCulex quinquefasciatusin experimental huts in Lomé. Endpoints were deterrence, exophily, blood feeding inhibition, and mortality. Insecticide susceptibility ofCulex quinquefasciatuswas assessed with permethrin (1%), DDT (4%), bendiocarb (0.1%), deltamethrin (0.5%, 0.05%), carbosulfan (0.4%), and chlorpyrifos methyl (0.4%). Total of 1,223Cx. quinquefasciatusfemales were collected. PermaNet 3.0 unwashed deterred 16.84%Culexmosquitoes. After 20 washes, it deterred 5.79% mosquitoes compared to 6.84% deterrence by unwashed PermaNet 2.0. PermaNet 3.0 induced mosquitoes to exit huts 50.48% and inhibited blood feeding 70.97% in unwashed state. After 20 washes, the net induced 42.91% mosquitoes to exit and inhibited 67.06% mosquitoes from blood feeding. PermaNet 3.0 gave 76% personal protection at zero wash and 69% protection after 20 washes. The net retained 7.1% insecticidal effect in the unwashed state and after 20 washes 6.5%.Cx. quinquefasciatuswas resistant to tested insecticides (6%–50% mortality). PermaNet 3.0 is a good control tool against mosquitoes. However,Cx. quinquefasciatusis less affected by PermaNet 3.0. The evaluation depicts the success of vector control innovations using pyrethroids and nonpyrethroids in combination on nets. Additional studies withCulexspecies are recommended to know whether the difference in blood feeding is interspecific (difference in vector behaviour) and not due to intertrial variability.

Exposure of pregnant mice to chlorpyrifos-methyl alters embryonicH19gene methylation patterns

The aim of this study was to identify whether chlorpyrifos methyl (CPM) exposure during pregnancy leads to changes in the methylation patterns of H19 gene. CPM 4, 20, 100 mg/kg bw/day was administered to 4 pregnant mice per group between 7 and 12 days post coitum (d.p.c.). Pregnant mice were killed at 13 d.p.c. The genomic methylation in primordial germ cells (PGCs) and fetal organs (the liver, intestine, and placenta) was examined. Four polymorphism sites in the H19 alleles of maternal (C57BL/6J) and paternal (CAST/Ei) alleles were identified at nucleotide position 1407, 1485, 1566, and 1654. The methylation patterns of 17 CpG sites were analyzed. The methylation level in male and female PGCs was not altered by CPM treatment in the maternal allele H19. The methylation level of the paternal H19 allele was altered in only male PGCs in response to the CPM treatment. The methylation level at a binding site for the transcriptional regulator CTCF2 was higher than that at the CTCF1 binding site in all CPM-treated groups. In the placenta, the aggregate methylation level of H19 was 56.89%in control group. But, those levels were ranged from 47.7% to 49.89% after treatment with increasing doses of CPM. H19 gene from the liver and intestine of 13 d.p.c. fetuses treated with CPM was hypomethylated as compared with controls, although H19 mRNA expression was unaltered. In the placenta, H19 expression was slightly increased in the CPM-treated group, although not significantly. IGF2 expression levels were not significantly changed in the placenta. In conclusion, CPM exposure during pregnancy alters the methylation status of the H19 gene in PGCs and embryonic tissues. We infer that these alterations are likely related to changes in DNA demethylase activity.

Dispersive liquid–liquid microextraction of organophosphorous pesticides using nonhalogenated solvents

Dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography and mass spectrometry (GC-MS) was applied to the determination of five organophosphorous pesticides (OPPs) in water samples. The analytes included in this study were prophos, diazinon, chlorpyrifos methyl, fenchlorphos, and chlorpyrifos. The use of nonhalogenated solvents (cyclohexane, heptane, and octane) as extraction solvents was investigated using acetone, acetonitrile, or methanol, as dispersion solvents. The combination of less polar dispersion solvents (1-propanol and 2-propanol) and nonhalogenated extraction solvents was also studied in dispersive liquid-liquid microextraction for the first time. Several experimental conditions were tested (nature and volume of extraction solvents, nature and volume of dispersion solvents, salting-out effect) and the corresponding enrichment factors and recoveries were evaluated. The best microextraction condition was obtained using 50 μL of cyclohexane and 0.3 mL of 1-propanol. The detection and quantification limits were in the low ppt range, with values between 3.3-8.0 ng/L and 11.0-26.6 ng/L, respectively. Relative standard deviations were between 6.6 and 13.1% for a fortification level of 500 ng/L. At the same fortification level, the relative recoveries (RR) of Alvito's dam water, Judeu's river water, and well water samples were in the range of 50.3-97.1%.

A disposable amperometric immunosensor for chlorpyrifos-methyl based on immunogen/platinum doped silica sol–gel film modified screen-printed carbon electrode

A disposable amperometric immunosensor for sensitive detection of chlorpyrifos-methyl (CM) has been developed by combining dual signal amplification of platinum colloid with an enzymatic catalytic reaction. The immunosensor was fabricated by modification of the screen-printed carbon electrodes (SPCE) with nanocomposites made by skillful doping of bovine serum albumin conjugated chlorpyrifos-methyl antigen (BSA-Ag) and platinum colloid into silica sol–gel. The scanning electron microscope (SEM) images and electrochemical measurements showed that platinum colloid domains in the nanocomposite material could enhance electron transfer and change the brittleness of the silica sol–gel. The immobilisation of BSA-Ag on the nanocomposite retained its immunoactivities, which allowed the immobilised BSA-Ag to effectively capture unbound Ab-HRP in the detection solution. A linear response to CM concentration was exhibited, ranging from 0.4 to 20ng/mL. Detection of CM with the presented method in soil or grape samples treated with CM matched the reference values well, which indicated that the proposed disposable immunosensor hold promising applications in environmental and food monitoring.

Estimation of Sample Processing Uncertainty of Large-Size Crops in Pesticide Residue Analysis

Sample processing procedure should result in analytical portions that are representative of the analytical sample, even if 1–5 g portion are withdrawn from a large-size crops. Therefore, the efficiency of sample processing should be regularly tested during method validation and internal quality control studies. In the scope of this study, sample processing uncertainty was investigated by surface treatment of the cucumber, papaya, and jackfruit representing large-size crops with radio-labelled chlorpyrifos methyl. After homogenization in a chopper, five small and five large test portions were withdrawn from “statistically” well-mixed materials and their residue content was determined with liquid scintillation counter, which provided a quick and well reproducible mode of quantitative determination of residues. The efficiency of sample processing characterized with the sampling constant, changed between 0.78 and 3.01 kg with typical value of 1.61 kg for processing at ambient temperature. Once the sampling constant was established, it was used to predict the uncertainty of sample processing for different test portion sizes. Uncertainty of sample processing at 30 g analytical portion varied between 4.70 and 10.55 %. Furthermore, addition of dry ice to papaya resulted in well-mixed samples as well as 50 % reduction in sampling constant value.

Headspace single-drop microextraction of common pesticide contaminants in honey–method development and comparison with other extraction methods

In the present study the main factors that may influence the headspace single-drop microextraction (HS-SDME) of common pesticide contaminants (diazinon, lindane, chlorpyrifos ethyl, p,p′-DDE, and endosulfan) that may occur in honey were determined and an analytical protocol was further developed by the use of a multivariate optimization. The HS-SDME analytical method developed and two more analytical protocols for the determination of pesticides in honey: (i) by direct SDME (D-SDME), and (ii) by liquid–liquid extraction (LLE), were further validated for the determination of target analytes. The three methods were also applied in the same real honey samples and results were further discussed. By D-SDME, LODs ranged from 0.04 µg kg−1 for β-endosulfan to 2.40 µg kg−1 for diazinon and repeatability expressed as %RSD from 3 for lindane to 15 for diazinon and chlorpyrifos methyl; by HS-SDME, LODs ranged from 0.07 µg kg−1 for p,p′-DDE to 12.54 µg kg−1 for chlorpyrifos methyl and repeatability expressed as %RSD from 11 for chlorpyrifos methyl to 19 for p,p′-DDE; by LLE, LODs ranged from 0.09 µg kg−1 for β-endosulfan to 19.31 µg kg−1 for diazinon and repeatability expressed as %RSD from 6 for p,p′-DDE to 11 for lindane. For all target pesticides but p,p′-DDE that could not be recovered by D-SDME method tested. The proposed HS-SDME optimized in this study was shown to be the method of choice for the determination of diazinon in honey whereas the most favourable analytical characteristics from the comparative study performed were achieved by D-SDME.

Comparison between GC-MS-SIM and GC-ECD for the determination of residues of organochlorine and organophosphorus pesticides in Brazilian citrus essential oils

Brazilian citrus essential oils (mandarin, orange, lemon, bergamot and tangerine) were analyzed for the determination of pesticides residues of organochlorine (aldrin, chlordane, dieldrin and dicofol) and organophosphorus (methyl chlorpyrifos, dimethoate, methidathion and methyl parathion) . A comparative study between gas chromatography-mass spectrometry in selective ion monitoring mode (GC-MS-SIM) and gas chromatography-electron capture detector (GC-ECD) was performed using solid phase extraction (SPE) with Florisil® cartridge for the pre-concentration of pesticides. The average recovery of pesticides was from 71 to 83% as determined by GC-MS-SIM analysis and 99 to 104% by GC-ECD. The limit of quantification was from 0.93 to 3.93 mg L-1 in GC-MS-SIM and 0.09 to 0.12 mg L-1 in GC-ECD. Fifteen samples of commercial Brazilian citrus essential oils were analyzed and six samples showed contamination with values above the maximum residue limit (MRL) allowed by the Codex Alimentarius.

Acetylcholinesterase based assay of eleven organophosphorus pesticides: finding of assay limitations

The study includes findings about limitations of acetylcholinesterase (AChE) based assay. Eleven organophosphorus pesticides: chlorpyrifos ethyl, chlorpyrifos methyl, DFP, dichlorvos, dimethoate, fenthion, paraoxon ethyl, paraoxon methyl, phosalone, pirimiphos methyl and pirimiphos ethyl were photometrically assayed using AChE as a recognition element. The study was carried out in order to find approachability of AChE based assay. In the first round, common organic solvents were tested for interfering in assay, since samples collection and extraction is a necessary part in samples processing. Isopropanol was found as the most convenient due to minimal inhibition not exceeding 5%. Though all analysed pesticides inhibit AChE in vivo, some of them are toxic after metabolisation. We found AChE based assay approachable for assay of DFP, paraoxons, and dichlorvos. These are oxoforms of organophosphorus pesticides. From thioforms of assayed pesticides, only fenthion was able significantly inhibit AChE in vitro. Electrochemical biosensor with AChE attached on platinum electrode was used for confirmation of interaction pesticide – AChE and complex stability estimation. DFP, paraoxons and dichlorvos were allowed to interact with AChE in biosensor. These pesticides were settled firmly in AChE active site as no spontaneous recovery of AChE activity was observed.

Inhibition of recombinant human carboxylesterase 1 and 2 and monoacylglycerol lipase by chlorpyrifos oxon, paraoxon and methyl paraoxon

Oxons are the bioactivated metabolites of organophosphorus insecticides formed via cytochrome P450 monooxygenase-catalyzed desulfuration of the parent compound. Oxons react covalently with the active site serine residue of serine hydrolases, thereby inactivating the enzyme. A number of serine hydrolases other than acetylcholinesterase, the canonical target of oxons, have been reported to react with and be inhibited by oxons. These off-target serine hydrolases include carboxylesterase 1 (CES1), CES2, and monoacylglycerol lipase. Carboxylesterases (CES, EC 3.1.1.1) metabolize a number of xenobiotic and endobiotic compounds containing ester, amide, and thioester bonds and are important in the metabolism of many pharmaceuticals. Monoglyceride lipase (MGL, EC 3.1.1.23) hydrolyzes monoglycerides including the endocannabinoid, 2-arachidonoylglycerol (2-AG). The physiological consequences and toxicity related to the inhibition of off-target serine hydrolases by oxons due to chronic, low level environmental exposures are poorly understood. Here, we determined the potency of inhibition (IC 50 values; 15 min preincubation, enzyme and inhibitor) of recombinant CES1, CES2, and MGL by chlorpyrifos oxon, paraoxon and methyl paraoxon. The order of potency for these three oxons with CES1, CES2, and MGL was chlorpyrifos oxon > paraoxon > methyl paraoxon, although the difference in potency for chlorpyrifos oxon with CES1 and CES2 did not reach statistical significance. We also determined the bimolecular rate constants ( k inact/ K I) for the covalent reaction of chlorpyrifos oxon, paraoxon and methyl paraoxon with CES1 and CES2. Consistent with the results for the IC 50 values, the order of reactivity for each of the three oxons with CES1 and CES2 was chlorpyrifos oxon > paraoxon > methyl paraoxon. The bimolecular rate constant for the reaction of chlorpyrifos oxon with MGL was also determined and was less than the values determined for chlorpyrifos oxon with CES1 and CES2 respectively. Together, the results define the kinetics of inhibition of three important hydrolytic enzymes by activated metabolites of widely used agrochemicals.

PAHs, PCBs, PBDEs and Pesticides in Cold‐Pressed Vegetable Oils

The aim of this study was to investigate levels of polychlorinated biphenyls (marker and dioxin-like congeners), polycyclic aromatic hydrocarbons (EPA 15 + 1), polybrominated diphenyl ethers (14 predominant congeners) and pesticides (74 compounds) in various cold-pressed vegetable oils. Poppy seed oil, rapeseed oil, sesame seed oil, pumpkinseed oil, hempseed oil, linaire oil, borage oil and evening star oil were investigated. Results of this study revealed that concentrations of PCBs, PBDEs and PAHs were low in majority of the investigated samples. However, high concentrations of organophosphorus insecticides were found. Chlorpyrifos methyl and pirimiphos methyl were the pesticide residues most commonly found in the studied oils. Concentration of 15 + 1 EPA PAHs was within the 17.85–37.16 μg kg−1 range, concentration of (marker) PCBs varied from 127 to 24,882 pg g−1, dioxin-like TEQ values were below 0.1 pg TEQ g−1. Concentration of PBDEs was below LOQ in most cases.

Determination of organophosphorous pesticides in the ppq range using a simple solid‐phase extraction method combined with dispersive liquid–liquid microextraction

Solid-phase extraction combined with dispersive liquid-liquid microextraction (SPE-DLLME) was applied for the extraction of six organophosphorous pesticides (OPPs) in water samples. The analytes considered in this study were determined by gas chromatography with mass spectrometry and included prophos, diazinon, chlorpyrifos methyl, methyl parathion, fenchlorphos and chlorpyrifos. Several extraction conditions (extraction solvent and elution/dispersion solvents nature, extraction solvent volume, elution solvent volume, water volume and sample volume) were tested for SPE-DLLME with these analytes and the best results were obtained using carbon tetrachloride as the extraction solvent and acetone as the elution/dispersion solvent. Calibration curves for the determination of OPPs in water samples were constructed in the concentration range of 10-100 ng/L. Limits of detection (LODs) ranged from 38 to 230 pg/L values that are below the maximum admissible level for drinking water (100 ng/L). Relative standard deviations (RSD) were between 8.6 and 10.4% for a fortification level of 100 ng/L. At the same fortification level, the relative recoveries (R.R.) of tap, well and irrigation water samples were in the range of 30.2-97.1%.

Validated dispersive liquid–liquid microextraction for analysis of organophosphorous pesticides in water

Dispersive liquid-liquid microextraction (DLLME) combined with gas chromatography and mass spectrometry (GC-MS) was applied to the determination of six organophosphorous pesticides (OPPs) in water samples. The analytes included in this study were prophos, diazinon, chlorpyrifos methyl, methyl parathion, fenchlorphos and chlorpyrifos. Several extraction and dispersion solvents were tested for dispersive liquid-liquid microextraction of these analytes and the best results were obtained using chloroform as extraction solvent and 2-propanol as dispersion solvent. Calibration curves of the analytes in water samples were constructed in the concentration range from 100 to 1100 ng/L for prophos, diazinon and methyl parathion and in the range from 100 to 1000 ng/L for chlorpyrifos methyl, fenchlorphos and chlorpyrifos. Limits of detection (LODs) were in the range of 1.5-9.1 ng/L and limits of quantification (LOQs) were in the range of 5.1-30.3 ng/L, below the maximum admissible level for drinking water. Relative standard deviations (RSDs) were between 6.5 and 10.1% in the concentration range of 100-1000 ng/L. The relative recoveries (%RRs) of tap, well and irrigation water samples fortified at 800 ng/L were in the range of 46.1-129.4%, with a larger matrix effect being detected in tap water.

Rapid extraction and detection of trace Chlorpyrifos-methyl in orange juice by surface-enhanced Raman spectroscopy

It is estimated that 20–50% of crops are saved from infestation through the use of pesticides. However, US inspectors find that more than 4% of fruits and vegetables imported exceed concentration levels considered safe for human consumption. This represents millions of tons of food brought to market annually that cannot be inspected using current hour-long laboratory methods. In an effort to provide inspectors with a simple, fast, field-usable analyzer and method, we have been developing a sampling device that includes surface-enhanced Raman spectroscopy (SERS) to detect, identify, and quantify pesticides below part-per-million (μg/mL) concentrations in approximately 10 min using a portable Raman analyzer. The entire method, including solvent extraction, solid-phase extraction, and SERS-detection, was used to detect 50 parts-per-billion (ppb) Chlorpyrifos-methyl (CPM) artificially added to orange juice in 12 min. The same method and analyzer can be readily adapted to other pesticides and foods.