Rapid screening for organochlorine and organophosphorus pesticides in milk using C18 and graphitized carbon black solid phase extraction cleanup

Abstract

A rapid, multiresidue, solid phase extraction (SPE) technique for the isolation and gas chromatographic determination of organochlorine and moderately polar organophosphorus pesticide residues in milk is described. Milk is sonicated with an acetonitrile‐acetone‐methanol mixture and centrifuged. The supernatant is subjected to a cleanup using both C₁₈ and graphitized carbon black SPE columns. The pesticide residues are determined by gas chromatography with electron capture and flame photometric detection. The method required minimal volumes of solvent and resulted in the production of minimal volumes of hazardous waste.     

Determination of organochlorine and organophosphorus pesticide residues in low moisture, nonfatty products using a solid phase extraction cleanup and gas chromatography

A multiresidue solid-phase extraction (SPE) method for the isolation and subsequent gas chromatographic determination of organochlorine and organophosphorus pesticide residues in low-moisture, nonfatty products is described. Residues are extracted from samples with an acetonitrile/water mixture. Cleanup of the extract is performed using graphitized carbon black and anion exchange SPE columns, and analysis is performed by gas chromatography with Hall electrolytic conductivity and flame photometric detection. Recovery data was obtained by fortifying corn, oats and wheat with pesticides. The average recoveries were 79-123% for eight organochlorine and 51-122% for 28 organophosphorus pesticide residues. The limit of quantitation for chlorpyriphos was 0.05 ppm using the Hall electrolytic conductivity detector and < 0.005 ppm using the flame photometric detector.     

Determination of organochlorine and organophosphorus pesticide residues in low moisture,nonfatty products using a solid phase extraction cleanup and gas chromatography

Abstract

A multiresidue solid‐phase extraction (SPE) method for the isolation and subsequent gas Chromatographie determination of organochlorine and organophosphorus pesticide residues in low‐moisture, nonfatty products is described. Residues are extracted from samples with an acetonitrile/water mixture. Cleanup of the extract is performed using graphitized carbon black and anion exchange SPE columns, and analysis is performed by gas chromatography with Hall electrolytic conductivity and flame photometric detection. Recovery data was obtained by fortifying corn, oats and wheat with pesticides. The average recoveries were 79–123% for eight organochlorine and 51–122% for 28 organophosphorus pesticide residues. The limit of quantitation for chlorpyriphos was 0.05 ppm using the Hall electrolytic conductivity detector and <0.005 ppm using the flame photometric detector.     

Rapid determination of residues of pesticides in honey by µGC-ECD and GC-MS/MS: Method validation and estimation of measurement uncertainty according to document No. SANCO/12571/2013

A simple and straightforward method for simultaneous determination of residues of 13 pesticides in honey samples (acrinathrin, bifenthrin, bromopropylate, cyhalothrin-lambda, cypermethrin, chlorfenvinphos, chlorpyrifos, coumaphos, deltamethrin, fluvalinate-tau, malathion, permethrin and tetradifon) from different pesticide classes has been developed and validated. The analytical method provides dissolution of honey in water and an extraction of pesticide residues by n-Hexane followed by clean-up on a Florisil SPE column. The extract was evaporated and taken up by a solution of an injection internal standard (I-IS), ethion, and finally analyzed by capillary gas chromatography with electron capture detection (GC-µECD). Identification for qualitative purpose was conducted by gas chromatography with triple quadrupole mass spectrometer (GC-MS/MS). A matrix-matched calibration curve was performed for quantitative purposes by plotting the area ratio (analyte/I-IS) against concentration using a GC-µECD instrument. According to document No. SANCO/12571/2013, the method was validated by testing the following parameters: linearity, matrix effect, specificity, precision, trueness (bias) and measurement uncertainty. The analytical process was validated analyzing blank honey samples spiked at levels equal to and greater than 0.010 mg/kg (limit of quantification). All parameters were satisfactorily compared with the values established by document No. SANCO/12571/2013. The analytical performance was verified by participating in eight multi-residue proficiency tests organized by BIPEA, obtaining satisfactory z-scores in all 70 determinations. Measurement uncertainty was estimated according to the top-down approaches described in Appendix C of the SANCO document using the within-laboratory reproducibility relative standard deviation combined with laboratory bias using the proficiency test data.     

Molecularly imprinted polymers for the detection of benomyl residues in water and soil samples

Benomyl is a benzimidazol fungicide used against various crop pathogens. Although banned in many countries, it is still widely used worldwide and is listed in different monitoring programs among the substances to be monitored to assess human exposure to pesticide residues. The assessment of benomyl is mainly based on the analysis of the residues of its most important metabolite, carbendazim. Existing methods often lack of selectivity and display a limited performance because of the presence of co-extracted compounds. Molecularly imprinted polymers (MIPs) offer an alternative methodology, adsorbing preferentially those target molecules for which the polymers are specifically prepared. In this study, we optimized the synthesis of a polymer imprinted with benomyl. Tests of specificity recognition showed a good performance for carbendazim compared with other similar pesticides. The mean recovery of benomyl (measured as carbendazim) from water samples was estimated to be 90% for MIPs while with real soil samples collected in Morocco the recovery efficiency was 62%. Preliminary tests also suggest that this MIP can implement traditional SPE techniques for assessing benomyl residual concentrations in environmental samples.     

Effect of clarification process on the removal of pesticide residues in red wine and comparison with white wine

The aim of this study was to determine the potential of seven clarifying agents to remove pesticides in red wine. The presence of pesticides in wine consists a great problem for winemakers and therefore, results on pesticide removal by clarification are very useful for taking a decision on the appropriate adsorbent. The selection of an efficient adsorbent can be based on data correlating pesticide removal in red wine to pesticides' properties, given the great number and variety of pesticides used. So, this experimental work is focused on the collection of results with regard to pesticide removal by clarification using a great number of pesticides and fining agents. A Greek red wine, fortified with single solutions and mixtures of 23 or 9 pesticides was studied. The seven fining agents, used at two concentrations, were activated carbon, bentonite, polyvinylpolypyrrolidone (PVPP), gelatin, egg albumin, isinglass-fish glue, and casein. Pesticides were selected with a wide range of properties (octanol–water partition coefficient (log K_ow) 2.7–6.3 and water solubility 0.0002–142) and belong to 11 chemical groups. Solid phase extraction (SPE) followed by gas chromatography (GC) with electron capture detector (ECD) were performed to analyze pesticide residues of the clarified fortified wine. The correlation of the clarifying agents' effectiveness to pesticide's chemical structure and properties (log K_ow, water solubility) was investigated. The antagonistic and/or synergistic effects, occurring among the pesticides in the mixtures, were calculated by indices. Pesticide removal effectiveness results of the red wine were compared to those obtained from a white wine under the same experimental conditions and discussed. The order of decreasing adsorbent effectiveness (mixture of 23 pesticides) was: activated carbon 40% > gelatin 23% > egg albumin 21% > PVPP 18% > casein 12% > bentonite 7%. Isinglass showed 12% removal at the highest permitted concentration. In the case of 9 pesticides mixture, the effectiveness was quite higher but the order remained the same compared to 23 pesticides mixture. The removal of each pesticide from its single solution was generally the highest (particularly for hydrophobic pesticides). Adsorption on fining agents is increased by increasing hydrophobicity and decreasing hydrophilicity of organic pesticide molecules.     

Hair as a marker for pesticides exposure

Rats were orally treated with mixtures of chlorinated pesticides. Hair was collected and analyzed for pesticide residues over a period of up to four weeks. Quantitative and qualitative analysis of the recovered pesticides in hair were determined using gas chromatography with electron capture detector. Results suggest that hair can be used as a biomarker for the monitoring of organochlorinated pesticide residues at low parts per billion levels. Chlorinated pesticides were also detected in human hair of environmentally exposed and occupationally exposed individuals, which indicates that hair can be used for monitoring pesticides exposure.     

Evaluation of C18 solid‐phase extraction cartridges for the isolation of select pesticides and metabolites

Abstract

Nine different C₁₈ solid‐phase extraction (SPE) cartridges were evaluated for their efficiency at extracting nine pesticides and two s‐triazine metabolites from spiked deionized water samples. The SPE cartridges were found to contain nitrogen (N) and/or phosphorus (P) contaminants and varied in their extraction efficiency for certain pesticides and metabolites. Four of the nine SPE cartridges gave acceptable (70 to 120%) pesticide and metabolite recovery percentages, while five cartridges had marginal (50 to 70%) to poor (< 50%) recoveries. Statistical analyses showed that the poor to marginal recoveries found for three compounds could not be explained by considering several indigenous chemical and physical traits of the cartridge. It is suggested that proper SPE cartridge selection for pesticide recovery should be evaluated using several different cartridges.     

Pesticide residues in thermal mineral water in Greece

Eight different hot springs (SPA) in Greece were monitored over a one-year survey for priority pesticide residues. A specific and effective procedure including solid phase extraction in combination with HPLC and GC analytical methods were applied. Samples that were sensitive to nitrogen-phosphorus (NPD) and/or electron capture (ECD) detectors were analysed by capillary gas chromatography. From the twenty-six water samples, pesticide residues were detected in fourteen of them (54%) but no one exceeding the European Union Maximum Acceptable Concentration (MAC). Lindane (gamma-BHC) was the most frequently detected pesticide. It was found in nine samples (35%) in concentrations from < 0.005 to 0.01 microg/L. Other pesticides detected were phorate (in five samples), propachlor (in two samples) and chlorpyriphos ethyl (in three samples) but in concentrations far below the permissible levels.     

Simultaneous determination of organochlorine and pyrethriod pesticide residues in the Chinese patent medicines by gas chromatography-tandem mass spectrometry

A simple, sensitive, reliable method was developed for the simultaneous determination of organochlorine and pyrethriod pesticide residues in Chinese patent medicines Six ingredient rehmannia pills and Xiaoyao pills. These pesticides were extracted by ethyl acetate. The extraction time and volume of ethyl acetate were optimized. Cleanup of extracts was performed with dispersive-solid phase extraction using graphitized carbon black as the sorbent. The determination of pesticides in the final extracts was carried out by gas chromatography–tandem mass spectrometry in multiple reaction monitoring mode (GC-MS/MS, MRM). The linearity of the calibration curves is good in matrix-matched standard and yields the coefficients of determination (R²) ≥0.99 for all of the target analytes. Under optimized conditions, the average recoveries (five replicates) for most pesticides range from 75.5% to 114.6%, and RSDs are less than 10.0%. The LODs of 18 pesticides in Six ingredient rehmannia pill and Xiaoyao pills are in the range of 0.01–8.82 μg kg^?1. The developed method meets the requirements of pesticide residue analysis and could be effectively used for routine analysis of the organochlorine and pyrethriod pesticide residues in Six ingredient rehmannia pills and Xiaoyao pills.     

Optimization of a pressurization methodology for extracting pore-water

Sediment toxicity can be assessed by conducting pore-water toxicity assays with standard water column organisms. Several methods have been developed for sampling pore-water. Centrifugation and pressurization methods are recommended when large volumes of pore-water are required to perform toxicity assays. Nevertheless, these methods involve sediment transportation and storage in laboratory, which can alter sediment toxicity. Therefore, an extraction method for large volumes that could be employed in the field site would be highly desirable. This study aimed to optimize and further evaluate an existing sediment pressurizing device with low construction costs, easy to carry and operate in the field, and presenting minimal chemical reactivity. The latter characteristic was achieved by lining the device interior with Teflon, by using large pore filters (50 microm), and by using an inert gas (nitrogen). Pore-water extraction efficiency and the toxicities of pore-water samples obtained by pressurization and by refrigerated centrifugation were compared. An artificial sediment (70% sand, 20% kaolin and 10% alpha-cellulose) spiked with an alcohol (phenol), a surfactant (SDS), a metal (copper), an organophosphate pesticide (parathion), and a natural sediment contaminated with acid mine drainage, were assayed for toxicity using Microtox assays. Sediment pressurization was found to be as efficient to extract pore-water as centrifugation, being more cost effective and adequate for field use.     

PESTICIDE RESIDUES IN THERMAL MINERAL WATER IN GREECE

Eight different hot springs (SPA) in Greece were monitored over a one-year survey for priority pesticide residues. A specific and effective procedure including solid phase extraction in combination with HPLC and GC analytical methods were applied. Samples that were sensitive to nitrogen-phosphorus (NPD) and/or electron capture (ECD) detectors were analysed by capillary gas chromatography.

From the twenty-six water samples, pesticide residues were detected in fourteen of them (54%) but no one exceeding the European Union Maximum Acceptable Concentration (MAC).

Lindane (γ-BHC) was the most frequently detected pesticide. It was found in nine samples (35%) in concentrations from <0.005 to 0.01 μg/L. Other pesticides detected were phorate (in five samples), propachlor (in two samples) and chlorpyriphos ethyl (in three samples) but in concentrations far below the permissible levels.     

Plant uptake of pesticides and human health: dynamic modeling of residues in wheat and ingestion intake

Human intake of pesticide residues from consumption of processed food plays an important role for evaluating current agricultural practice. We take advantage of latest developments in crop-specific plant uptake modeling and propose an innovative dynamic model to estimate pesticide residues in the wheat-environment system, dynamiCROP. We used this model to analyze uptake and translocation of pesticides in wheat after foliar spray application and subsequent intake fractions by humans. Based on the evolution of residues in edible parts of harvested wheat we predict that between 22 mg and 2.1 g per kg applied pesticide are taken in by humans via consumption of processed wheat products. Model results were compared with experimentally derived concentrations in wheat ears and with estimated intake via inhalation and ingestion caused by indirect emissions, i.e. the amount lost to the environment during pesticide application. Modeled and measured concentrations in wheat fitted very well and deviate from less than a factor 1.5 for chlorothalonil to a maximum factor 3 for tebuconazole. Main aspects influencing pesticide fate behavior are degradation half-life in plant and time between pesticide application and crop harvest, leading to variations in harvest fraction of at least three orders of magnitude. Food processing may further reduce residues by approximately 63%. Intake fractions from residues in sprayed wheat were up to four orders of magnitude higher than intake fractions estimated from indirect emissions, thereby demonstrating the importance of exposure from consumption of food crops after direct pesticide treatment.     

Development,validation of QuEChERS-based method for simultaneous determination of multiclass pesticide residue in milk,and evaluation of the matrix effect

Extraction and quantification of pesticide residue from the milk matrix at or below the established maximum residue limit (MRL) is a challenging task for both analytical chemists and the regulatory institutions to take corrective actions for the human health and safety. The main aim of the study is to develop a simple rapid and less expensive QuEChERS extraction and cleanup method for simultaneous analysis of 41 multiclass pesticide residue in milk by gas chromatography-electron capture detector (GC-ECD), followed by confirmation of the residues with gas chromatography-mass spectrometer (GC-MS). Effect of sorbent type, temperature, spiking concentration, matrix effect (ME), measurement uncertainty (MU), inter- and intra-assay repeatability, reproducibility of recovery, and trueness of the results were investigated to validate the effectiveness of the method. Limit of determination (LOD) and limit of quantitation (LOQ) for all the analytes ranged within 0.001–0.02 and 0.002–0.05 µg mL^?1, respectively. The % recovery of all the pesticides ranged between 91.38 and 117.56% with relative standard deviation (RSD) below 2.79%. The MU for all the analytes was ≤29% of respective LOQs, and except for few pesticides, the ME was largely negative. The method fulfilled all the SANTE guidelines and thus can be extended for routine analysis of multiclass pesticide residue in milk.     

Contamination levels of selected organochlorine and organophosphate pesticides in the Selangor River, Malaysia between 2002 and 2003

In Malaysia, rivers are the main source of public water supplies. This study was conducted from 2002 to 2003 to determine the levels of selected organochlorine and organophosphate pesticides in the Selangor River in Malaysia. Surface water samples have been collected seasonally from nine sites along the river. A liquid-liquid extraction followed by gas chromatography-mass spectrometry technique was used to determine the trace levels of these pesticide residues. The organochlorine pesticides detected were lindane, heptachlor, endosulfan, dieldrin, endosulfan sulfate, o,p'-DDT, p,p'-DDT, o,p'-DDE and p,p'-DDE whereas for organophosphate pesticides, they were chlorpyrifos and diazinon. At the river upstream where a dam is located for public water supply, incidents of pesticide levels exceeding the European Economic Community Directive of water quality standards have occurred. Furthermore, the wetland ecosystems located at the downstream of the river which houses the fireflies community is being threatened by occasional pesticide levels above EPA limits for freshwater aquatic organisms. The occurrence of these residual pesticides in the Selangor River can be attributed to the intense agriculture and urban activity.     

Monitoring of pesticide residues in a cotton crop soil

This paper reports on the residues of methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate), trifluralin (alpha, alpha, alpha-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), endosulfan [(1, 4, 5, 6, 7, 7-hexachloro-8, 9, 10-trinorborn-5-en-2, 3-ylenebismethylene) sulfite] and dimethoate (O, O-dimethyl S-methylcarbamoylmethyl phosphorodithioate) in a cotton crop soil. Soil samples (0-15 cm) were collected at different periods from the cotton crop farm and subjected to Soxhlet extraction. The extracted material was analysed after clean-up by a HP5890 II gas chromatograph equipped with a 63Ni electron-capture detector (ECD-63Ni) and fitted with a 25 m x 0.2 mm i.d. fused silica capillary column [Ultra-2 (5% phenylmethyl polysiloxane)]. The recoveries of the pesticide residues from the spiked control soil were determined after Soxhlet extraction and C18 cartridges clean-up by using radiotracer techniques with the corresponding 14C-pesticides. The results show that in the cotton crop soil the pesticide residues under study were present in the range of 0.1 to 0.4 mg.kg-1. Endosulfan was found to be rapidly degraded in the soil and formed a sulfate metabolite.     

Pesticide residues in Portuguese strawberries grown in 2009–2010 using integrated pest management and organic farming

Pesticides are among the most widely used chemicals in the world. Because of the widespread use of agricultural chemicals in food production, people are exposed to low levels of pesticide residues through their diets. Scientists do not yet have a total understanding of the health effects of these pesticide residues. This work aims to determine differences in terms of pesticide residue content in Portuguese strawberries grown using different agriculture practices. The Quick, Easy, Cheap, Effective, Rugged, and Safe sample preparation method was conducted and shown to have good performance for multiclass pesticides extraction in strawberries. The screening of 25 pesticides residue was performed by gas chromatography?Ctandem mass spectrometry. In quantitative validation, acceptable performances were achieved with recoveries of 70?C120 and <12?% residual standard deviation for 25 pesticides. Good linearity was obtained for all the target compounds, with highly satisfactory repeatability. The limits of detection were in the range of 0.1?C28???g/kg. The method was applied to analyze strawberry samples from organic and integrated pest management (IPM) practices harvested in 2009?C2010. The results showed the presence of fludioxonil, bifenthrin, mepanipyrim, tolylfluanid, cyprodinil, tetraconazole, and malathion when using IPM below the maximum residue levels.     

A wind tunnel for measuring the gaseous losses of environmental chemicals from the soil/plant system under field-like conditions

Volatilization from treated areas is a major source of pesticide residues in air, fog, and rain. This may lead to long-range transport of pesticide residues to remote areas. Up to now most information on pesticide volatilization has come from laboratory experiments under controlled conditions. A new system has been designed and developed to measure the volatile losses of¹⁴C-labelled chemicals after application; the method compares with agricultural practice of treating soils or plants grown in lysimeters. Sensitive analytical methods guarantee a distinction between residues of unchanged pesticide, its metabolites or¹⁴CO₂ as a mineralization product released into the air.     

Bound pesticide residues in soils: a review

This article is a review of the current state of knowledge regarding the formation and biological/environmental significance of bound pesticide residues in soils. We begin by defining various terms used in our discussions and identifying the types/classes of pesticides which may be added to soil and interact with it. We then consider various soil properties and aspects of land management which will influence the nature and degree of the soil-pesticide association and discuss the possible physical and chemical binding mechanisms. We then move on to consider the role of microorganisms and other forms of soil biota in bound residue formation and the bioavailability of soil-borne pesticide residues. The review ends with a consideration of the significance of bound pesticide residues.     

Persistent organochlorine pesticide residues in fish, sediments and water from Lake Bosomtwi, Ghana

Some organochlorine pesticide residues in tilapia fish (Tilapiazilli), sediment and water samples from Lake Bosomtwi (the largest natural lake in Ghana) were determined to find out the extent of pesticide contamination and accumulation in the lake. The extracted residues were analyzed on a micro-capillary gas chromatograph equipped with electron capture detector. DDE (p,p'-1,1-dichloro-2,2-bis-(4-chlorophenyl)ethylene) was the predominant residue in all the samples analyzed; detected in 82% of water samples, 98% of sediment samples and 58% of fish samples at concentrations of 0.061+/-0.03 ng g(-1), 8.342+/-2.96 ng g(-1) and 5.232+/-1.30 ng g(-1), respectively. DDT (p,p'-1,1,1-trichloro-2,2-bis-(4-chlorophenyl)ethane) was detected in 78% at a mean concentration 0.012+/-0.62 ng g(-1) of water samples analyzed. The mean concentrations of DDT in sediments and fish were 4.41+/-1.54 ng g(-1) and 3.645+/-1.81 ng g(-1), respectively. The detection of lower levels of DDT than its metabolite, DDE, in the samples implies that the presence of these contaminants in the lake is as result of past usage of the pesticides.