The effect of soil moisture content on the sorption of five sterol biosynthesis inhibiting fungicides as a function of their physicochemical properties

We investigated the sorption of five widely used sterol biosynthesis inhibitor fungicides (SBIs: flusilazole, propiconazole, epoxiconazole, fenpropimorph and prochloraz) on a loam soil to assess availability of the SBI residues that are usually left in soil after crop treatments. We focused particularly on the soil moisture content effect, which is poorly documented and is difficult to investigate under realistic conditions. SBI sorption was determined (using diuron as a reference) at two soil moisture contents (26.1% and 46.6% w/w) over a period of 3 weeks using a direct soil solution sampling method. After 24 h of contact, <1% of each applied fungicide was recovered in the soil solution. Despite their low availability in the liquid phase, long‐term sorption was observed for all the compounds, reducing concentrations in the soil solution and doubling the value of the partition coefficient. Significant effects of soil moisture on long‐term sorption were observed, depending on the properties of the chemicals and the sorption mechanisms. Wershaw's humus model (humic substances have a membrane‐like structure) was adapted to fit our observations. Low soil moisture content is assumed to modify the structure of humic substances and to generate hydrophobic surfaces, which favour sorption of hydrophobic fungicides (flusilazole, propiconazole and epoxiconazole). This effect is likely to decrease with the increase in the hydrophobic character of non‐ionic pesticides. It becomes adverse for the more hydrophilic compounds (diuron), which are more sorbed at high soil moisture content due to their higher affinity for hydrophilic regions of humus and to diffusion. Soil moisture effects are more complex when compounds are likely to be protonated in soil. Weakly basic compounds (prochloraz) may partition rapidly into the liquid‐like interior of humus at low soil moisture content but increased diffusion at high soil moisture content may cause additional sorption by ion exchange at colloid surfaces. Strongly basic compounds (fenpropimorph) may essentially adsorb due to ionic interactions with colloids, and their sorption is enhanced at high soil moisture content due to diffusion. Consequences for environmental fate and biological activity of pesticides are briefly discussed. © 2000 Society of Chemical Industry     

Sorption of aged dicamba residues in soil

The effect of aging (residence time in soil) on dicamba (3,6-dichloro-2-methoxybenzoic acid) and a major metabolite, 3,6-dichlorosalicylic acid (3,6-DCSA) sorption was determined in an unamended and a carbon-amended sandy loam and in a silt loam soil. During the incubation, sequential solvent extraction with 0.01 M calcium chloride solution and aqueous acetonitrile + hydrochloric acid was used to determine the solution and sorbed concentrations of dicamba and 3,6-DSCA, and sorption coefficients were calculated. Dicamba was weakly sorbed to soil (Kd < 0.7). In contrast to some other classes of pesticides, sorption of dicamba did not significantly increase with aging, at least not until < 15% of the applied dicamba remained. 3,6-DSCA was strongly sorbed to soil (Kd > 8) and the Kd-a value increased by a factor of 2-6 during a 28-day aging period. Addition of a carbon source to the soil had minimal effect on the strength of sorption of aged dicamba. However, it did appear to decrease 3,6-DSCA availability to soil micro-organisms; once formed 3,6-DSCA was not further mineralized. While it appears that sorption can be well characterized for weakly sorbed pesticides using the batch equilibration method with freshly treated soils, this procedure may not be adequate for more strongly sorbed pesticides and their degradates.     

Control of the mushroom phorid fly, Megaselia halterata (Wood), with plant extracts

BACKGROUND: The most serious insect pest problems affecting the cultivation of mushroom [Agaricus bisporus (Lange) Imbach] in Turkey are mushroom flies (sciarids, cecids and phorids). Mushroom phorid fly, Megaselia halterata (Wood), is the most common insect pest species during April‐October. The aim of this study was to evaluate the potential for eight botanical materials (two commercial neem‐based products and six hot‐water plant extracts) to control M. halterata populations in three successive growing periods. RESULTS: Treatment efficacy was evaluated by assessing adult emergence and sporophore damage rates compared with that of a standard insecticide, chlorpyrifos‐ethyl (positive control). All plant extracts caused significant reductions in the mean number of emerging adults and sporophore damage rates compared with the water‐treated control (negative control). Reduction in adult emergence in both neem treatments, Neemazal and Greeneem oil, was greater than that in the positive control. While Neemazal and Origanum onites L. extract had significantly lower sporophore damage rates than the positive control, there were no significant differences between the chlorpyrifos‐ethyl, Greeneem oil and Pimpinella anisum L. extract treatments. CONCLUSION: The results suggest that both neem products and hot‐water extracts of O. onites and P. anisum may be potential alternatives to conventional pesticides for the control of mushroom phorid fly. Copyright © 2008 Society of Chemical Industry     

Antifeedant effect of commercial chemicals and plant extracts against Schistocerca americana (Orthoptera: Acrididae) and Diaprepes abbreviatus (Coleoptera: Curculionidae)

BACKGROUND: The deterrent effect of seven commercial compounds against Schistocerca americana (Drury) nymphs and Diaprepes abbreviatus L. adults, two important citrus pests, was investigated. Extracts of three Florida local plants were also tested as deterrents. Antifeedant activity was assayed using a leaf‐disk bioassay in choice and no‐choice tests. The residual activity of the commercial compounds that significantly deterred the insects was assayed by applying them to foliage of citrus plants exposed to three time intervals of sunlight. RESULTS: Sabadilla, azadirachtin and ryanodine effectively deterred S. americana, whereas rotenone, sabadilla and ryanodine reduced the feeding activity of D. abbreviatus. Methanol and methylene chloride extracts of Ceratiola ericoides Michaux deterred D. abbreviatus, but only methylene chloride extract dissuaded S. americana. Methanol extract of Ardisia crenata Sims functioned as a feeding deterrent against both S. americana and D. abbreviatus, but only the latter species was deterred by methylene chloride extract of A. crenata. Extracts of Illicium parviflorum Michaux ex Ventetat only dissuaded the insects in choice bioassays. Rapid loss of effectiveness was observed under field conditions. Sabadilla was the only compound that maintained its antifeedant properties in the field, but only against S. americana. CONCLUSION: Based on their deterrency, some of the commercial products and plant extracts have potential for use as substitute crop protectants against the pest species tested. Copyright © 2011 Society of Chemical Industry     

Current- and past-use pesticide prevalence in drainage ditches in the Lower Mississippi Alluvial Valley

BACKGROUND: Pesticide application is common in agriculture and often results in applied pesticides entering adjacent aquatic systems. This study seasonally analyzed a suite of 17 current‐ and past‐use pesticides in both drainage waters and sediments to evaluate the prevalence of pesticides in drainage ditches across the Lower Mississippi Alluvial Valley (LMAV). RESULTS: There were significantly higher concentrations (P < 0.05) of current‐use than past‐use pesticides; however, there were consistently high numbers of detections of past‐use pesticides in sediments. Sediment pesticide concentrations were an order of magnitude higher (150–1035 µg kg^?1) than water samples (6–20.9 µg L^?1). Overall, 87% of all samples analyzed for current‐ and past‐use pesticides were non‐detects. p,p′‐DDT was detected in 47.5% of all drainage waters and sediments sampled. There were significant correlations (0.372 ≥ r²≤0.935) between detected current‐use water and sediment concentrations, but no significant correlations between past‐use water and sediment concentrations. CONCLUSION: Overall, there was a high percentage (87%) of sediment and water samples that did not contain detectable concentrations above the lower limit of analytical detection for each respective pesticide. This lack of pesticide prevalence highlights the improved conditions in aquatic systems adjacent to agriculture and a potential decrease in toxicity associated with pesticides in agricultural landscapes in the LMAV. Copyright © 2011 Society of Chemical Industry     

Perspective: present pesticide discovery paradigms promote the evolution of resistance – learn from nature and prioritize multi‐target site inhibitor design

For many years, the emphasis of industry discovery programs has been on finding new target sites of pesticides and finding pesticides that inhibit single targets. There had been an emphasis on genomics in finding single targets for potential pesticides. There is also the claim that registration of single target inhibiting pesticides is simpler if the mode of action is known. Conversely, if one looks at the evolution of resistance from an epidemiological perspective to ascertain which pesticides have been the most recalcitrant to evolutionary forces, it is those that have multiple target sites of action. Non‐target‐site resistances can evolve to multi‐target‐site inhibitors, but these resistances can often be overcome by structural modification of the pesticide. Industry has looked at pest‐toxic natural products as pesticide leads, but seems to have abandoned those where they can find no single target of action. Perhaps nature has been intelligent and evolved many natural products that are synergistic multi‐target‐site inhibitors, and that is why natural compounds have been active for millennia? We should be learning from nature while combining new chemistry technologies with vast accrued databases and computer aided design allowing fragment‐based discovery and scaffold hopping to produce multi‐target site inhibitors instead of single target pesticides. © 2019 Society of Chemical Industry     

柑橘中13种农药残留量的检测

本文介绍了柑橘样品中农药残留监测分析的研究，结果表明利用乙腈对柑橘中氧乐果等13种农药进行提取、经固相萃取柱净化、气相色谱仪带FPD、ECD检测器定量检测，13种农药分离的效果良好，回收率为82．3％～95．0％，相对标准偏差〈5．0％。该方法是对NY／T761—2008的优化．指出了实际分析过程中应注意的问题。优化后的方法精密度高、重现性好，可以为广东省柑橘农药残留检测工作中推广应用。     

固体增溶/分散技术制备啶虫脒可溶粒剂

为了实现对难溶或微溶农药的高效利用,并满足速效、低毒和绿色环保的要求,采用医药研究中常用的固体增溶/分散技术,以聚乙二醇10000为固体增溶/分散介质,TANEMULCON1为分散剂,氯化铵为崩解剂,经混合造粒制备了啶虫脒可溶粒剂。当配方(以质量分数计)为啶虫脒30%、PEG10000 60%、分散剂TANEMULCON1 4%、氯化铵补足至100%时,啶虫脒可溶粒剂具有性质稳定、崩解速率快、能形成稳定的真溶液的特性。表明固体增溶/分散技术是将难溶于水的农药制备成可溶粒剂的一种简单、优良的新方法。     

降解残留有机农药的微生物资源研究进展

有机农药污染已成为一个世界性问题,微生物在环境农药残留修复中起着重要作用。对降解有机磷、有机氯、拟除虫菊酯类和有机氮等农药的微生物种属资源以及相关酶资源和基因资源的研究进展进行了综述,分析了近年来该领域中对微生物资源的开发和利用状况,并讨论了在环境修复、生物防治和生物肥料等方面多功能化应用微生物资源,同时保障转基因生物安全,避免对环境造成二次污染等应成为该领域重要的研究方向。     

Field leaching of pesticides at five test sites in Hawaii: modeling flow and transport

BACKGROUND: Physically based tier‐II models may serve as possible alternatives to expensive field and laboratory leaching experiments required for pesticide approval and registration. The objective of this study was to predict pesticide fate and transport at five different sites in Hawaii using data from an earlier field leaching experiment and a one‐dimensional tier‐II model. As the predicted concentration profiles of pesticides did not provide close agreement with data, inverse modeling was used to obtain adequate reactive transport parameters. The estimated transport parameters of pesticides were also utilized in a tier‐I model, which is currently used by the state authorities to evaluate the relative leaching potential. RESULTS: Water flow in soil profiles was simulated by the tier‐II model with acceptable accuracy at all experimental sites. The observed concentration profiles and center of mass depths predicted by the tier‐II simulations based on optimized transport parameters provided better agreements than did the non‐optimized parameters. With optimized parameters, the tier‐I model also delivered results consistent with observed pesticide center of mass depths. CONCLUSION: Tier‐II numerical modeling helped to identify relevant transport processes in field leaching of pesticides. The process‐based modeling of water flow and pesticide transport, coupled with the inverse procedure, can contribute significantly to the evaluation of chemical leaching in Hawaii soils. Copyright © 2011 Society of Chemical Industry     

Spatially resolved quantification of agrochemicals on plant surfaces using energy dispersive X‐ray microanalysis

BACKGROUND: In the present study the principle of energy dispersive X‐ray microanalysis (EDX), i.e. the detection of elements based on their characteristic X‐rays, was used to localise and quantify organic and inorganic pesticides on enzymatically isolated fruit cuticles. Pesticides could be discriminated from the plant surface because of their distinctive elemental composition. RESULTS: Findings confirm the close relation between net intensity (NI) and area covered by the active ingredient (AI area). Using wide and narrow concentration ranges of glyphosate and glufosinate, respectively, results showed that quantification of AI requires the selection of appropriate regression equations while considering NI, peak‐to‐background (P/B) ratio, and AI area. The use of selected internal standards (ISs) such as Ca(NO₃)₂ improved the accuracy of the quantification slightly but led to the formation of particular, non‐typical microstructured deposits. The suitability of SEM‐EDX as a general technique to quantify pesticides was evaluated additionally on 14 agrochemicals applied at diluted or regular concentration. CONCLUSION: Among the pesticides tested, spatial localisation and quantification of AI amount could be done for inorganic copper and sulfur as well for the organic agrochemicals glyphosate, glufosinate, bromoxynil and mancozeb. Copyright © 2009 Society of Chemical Industry     

水中12 种农药的固相萃取及GC-MS 测定方法研究

利用气相色谱法进行测定 ,用己烷和丙酮做洗脱溶剂 ,用 Isolute TMENV+SPE柱对水中 12种农药的固相萃取方法进行了研究 ,并用 MS选择离子模式进行了定量分析。水中添加浓度为 1、5、10μg· L-1三个水平 ,其中 11种农药的添加回收率在 6 2 .3%～ 10 5.0 % ,只有克百威的回收率较低。     

Biopesticide based sustainable pest management for safer production of vegetable legumes and brassicas in Asia and Africa

Vegetables are one of the important crops which could alleviate poverty and malnutrition among the smallholder farmers in tropical Asia and Africa. However, a plethora of pests limit the productivity of these crops, leading to economic losses. Vegetable producers overwhelmingly rely on chemical pesticides in order to reduce pest‐caused economic losses. However, over‐reliance on chemical pesticides poses serious threats to human and environmental health. Hence, biopesticides offer a viable alternative to chemical pesticides in sustainable pest management programs. Baculoviruses such as nucleopolyhedrovirus (NPV) and granulovirus (GV) have been exploited as successful biological pesticides in agriculture, horticulture and forestry. Maruca vitrata multiple nucleocapsid NPV (MaviMNPV) was found to be a unique baculovirus specifically infecting pod borer on food legumes, and it has been successfully developed as a biopesticide in Asia and Africa. Entomopathogenic fungi also offer sustainable pest management options. Several strains of Metarhizium anisopliae and Beauveria bassiana have been tested and developed as biopesticides in Asia and Africa. This review specifically focuses on the discovery and development of entomopathogenic virus and fungi‐based biopesticides against major pests of vegetable legumes and brassicas in Asia and Africa. © 2019 Society of Chemical Industry     

Measurement of pesticide residues in peppers by near‐infrared reflectance spectroscopy

BACKGROUND: Peppers are a frequent object of food safety alerts in various member states of the European Union owing to the presence in some batches of unauthorised pesticide residues. This study assessed the viability of near‐infrared reflectance spectroscopy (NIRS) for the measurement of pesticide residues in peppers. Commercially available spectrophotometers using different sample‐presentation methods were evaluated for this purpose: a diode‐array spectrometer for intact raw peppers and two scanning monochromators fitted with different sample‐presentation accessories (transport and spinning modules) for crushed peppers and for dry extract system for infrared analysis (DESIR), respectively. RESULTS: Models developed using partial least squares–discriminant analysis (PLS2‐DA) correctly classified between 62 and 68% of samples by presence/absence of pesticides, depending on the instrument used. At model validation, the highest percentage of correctly classified samples—75 and 82% for pesticide‐free and pesticide‐containing samples respectively—were obtained for intact peppers using the diode‐array spectrometer. CONCLUSION: The results obtained confirmed that NIRS technology may be used to provide swift, non‐destructive preliminary screening for pesticide residues; suspect samples may then be analysed by other confirmatory analytical methods. Copyright © 2010 Society of Chemical Industry     

Chimeric mice with humanized liver as a model for testing organophosphate and carbamate pesticide exposure

BACKGROUND

Diagnosis of acute intoxication with organophosphate (OP) or carbamate (CM) pesticides in humans is achieved by measuring plasma butyrylcholinesterase (BuChE) activity. However, BuChE activity is not an ideal biomarker in experimental animal models. The aim of this study was to establish an experimental mouse model for evaluating exposure to OP and CM pesticides by monitoring BuChE activity using chimeric mice in which the liver was reconstituted with human hepatocytes.

RESULTS

A single oral administration of acephate (300 mg/kg), chlorpyrifos (10 mg/kg), fenobucarb (300 mg/kg) or molinate (250 mg/kg) in chimeric mice led to inhibition of >95%, > 95%, 28% and 60% of plasma BuChE activity after 7, 0.5, 0.5 and 7 h, respectively. Dose‐dependent decreases in plasma BuChE activity were also observed for acephate and chlorpyrifos. A 5‐day repeated‐dose study with 10 or 30 mg/kg acephate found a constitutive reduction in plasma BuChE activity to 80% and 70% of pre‐dose levels, respectively.

CONCLUSION

Changes in plasma BuChE activity in chimeric mice with humanized liver clearly reflected the exposure levels of OP and CM pesticides. These results suggest that the humanized‐liver mouse model may be suitable for estimating levels of exposure to these pesticides in humans. © 2017 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Zanthoxylum piperitum (DC), a potential feeding deterrent for mammals: studies with Microtus ochrogaster (Wagner)

Total extract from the fruit of Szechuan pepper (Zanthoxylum piperitum DC), the volatile components of the extract and a non‐volatile fraction containing alkylamides (NVA fraction) are feeding deterrents for rats. The present study investigated the effectiveness of these natural repellents in prairie voles (Microtus ochrogaster Wagner). Two‐choice feeding trials were conducted during which food‐deprived voles were offered choices between oat‐bran wafers. In Experiment 1, 10 voles were given three sets of feeding trials, each 2 h long. Baseline consumption was established during the first set of two trials by offering a choice between two oat‐bran wafers dipped in ethanol, the control solvent. During the second set of two trials the voles were given a choice between an oat‐bran wafer dipped in ethanol and a wafer dipped in Zanthoxylum extract. During the third set the voles were given a choice between a wafer served on top of a screened dish containing a sample of ethanol and a wafer served on top of a dish containing a sample of extract. In this manner the voles were exposed to volatile compounds emanating from the extract but could not contact it. Wafers dipped in extract were almost completely avoided. The volatile components of extract also significantly reduced food intake. In Experiment 2, habituation to the volatile constituents of extract was examined in 16 Zanthoxylum‐naïve voles. Baseline consumption was established by offering two wafers served on top of screened dishes containing ethanol. This was followed by twelve tests during which a choice between a wafer served above a sample of ethanol and a wafer served above a sample of extract was given. The voles failed to habituate to the volatile components of extract, consistently consuming less of the wafers served above extract. In Experiment 3 a dose‐response curve to Zanthoxylum extract was established, using 12 stimulus‐naïve voles. After baseline consumption was established, the animals were given two tests each, presenting a choice between a control wafer and a wafer dipped in a dilution of extract (0.001–100 g liter^?1). Only concentrations of 10 and 100 g liter^?1 reduced food intake. In Experiment 4 the effects of the non‐volatile fraction of extract were compared to those of whole extract. Vegetable oil was used as solvent. Eight stimulus‐naïve voles were given two tests with a choice between an oil‐dipped and an extract‐dipped wafer. A second group of eight voles received two tests with a choice between an oil‐dipped and NVA‐dipped wafer. Extract‐dipped wafers were avoided, but the NVA fraction had no effect on food consumption. Copyright © 2004 Society of Chemical Industry     

Risk assessment for honey bees and pesticides—recent developments and ‘new issues’

In 2008, major areas of discussion at the ICPBR Bee Protection Group meeting were the development of a honey bee risk assessment scheme for systemic pesticides and revision of the test guidelines for semi‐field and field studies. The risk assessment scheme for systemic pesticides is based on analysis of conditions for exposure of bees to residues. These are based on a stepwise approach, starting with simple calculations based on existing data in dossiers and progressing to higher‐tier semi‐field and field studies (the guidelines for these have been modified in line with this). The proposed scheme has been tested with data packages of high‐ and low‐risk PPPs. A future area of interest for the group may be the risks posed by guttation fluid containing systemic pesticides. A recent paper on ‘Translocation of neonicotinoid insecticides from coated seeds to seedling guttation drops: a novel way of intoxication for bees’ has focused significant interest on the possible risks posed by the presence of residues of systemic pesticides in guttation fluid to water‐collecting honey bees. The occurrence of guttation and the presence of pesticide residues in the fluid are discussed, together with remaining questions that will need to be addressed in answering whether such a route of exposure may pose a risk to honey bees. © Crown copyright 2010. Reproduced with permission of Her Majesty's Stationery Office. Published by JohnWiley & Sons, Ltd.     

Selectivity of pesticides used on cotton (Gossypium hirsutum) to Trichogramma pretiosum reared on two laboratory-reared hosts

The side-effects of pesticides (insecticides, fungicides, herbicides and plant growth regulators) used on cotton were tested on adults and pupae of Trichogramma pretiosum Riley reared in the laboratory on two different hosts, the Angoumois grain moth (Sitotroga cerealella Olivier) and the Mediterranean flour moth (Ephestia kuehniella (Zeller)). The eggs of the host enclosing the parasitoid pupae received direct pesticide sprays, while the adults of the parasitoid were exposed to the pesticides through contact with residues on sprayed eggs offered to parasitism. Alpha-cypermethrin, carbosulfan, deltamethrin, endosulfan, profenofos and zeta-cypermethrin were highly noxious to the parasitoid, significantly reducing the percentage of emergence and parasitism of T. pretiosum developing in E. kuehniella or S. cerealella eggs. However, the pupal stage of the parasitoid developing in S. cerealella eggs was less susceptible to alpha-cypermethrin and deltamethrin. Lufenuron and metamidophos greatly reduced the percentage of adult emergence from eggs of both hosts, while novaluron only interfered on this variable when the wasps were developing in E. kuehniella eggs. However, lufenuron and monocrotophos had no effect on the parasitoid pupae of T. pretiosum developing in E. kuehniella eggs. Chlorfluazuron, diafenthiuron, diflubenzuron, fentin hydroxide, mepiquat chloride, novaluron, thiacloprid and triflumuron did not affect T. pretiosum emergence when eggs of S. cerealella enclosing pupae of the wasps were surface treated. The pesticides azoxystrobin, carbendazin + thiram, mepiquat chloride and novaluron had no effect on the ability of the wasps to parasitise E. kuehniella eggs. However, only mepiquat chloride did not affect the percentage of F1 wasps emerging from E. kuehniella eggs. The remaining pesticides moderately reduced the percentage of emergence and parasitism of the wasps when they had contact with the chemicals during their pupal or adult stage. Thus there were differences in pesticide toxicity according to the host used for parasitoid development. These differences were hypothesised to occur because of differences in egg morphology and parasitoid performance.     

Effect of crude oil pollution on organic carbon and humus content in grey-brown soils in Mangyshlak, Pre-Caspian Sea Region

The organic carbon and humus content in oil polluted brown and grey-brown soils in Mangyshlak,Pre-Caspian Sea Region,was analyzed from 2000 to 2008.The results indicated that bitumen substances from crude oil pollution deteriorated the soil property,however,the organic carbon content increased significantly.The products of oil pollution changed the composition of car-bonaceous substances which formed soil humus,and changed the ratios of the humus components.Residual insoluble carbon increased with the rise of oil organic carbon.The mobility of humus components was significantly increased because of the high oxidation-reduction process in the topsoil,and the humus content and microorganism activity increased.The organic carbon content increased significantly,while it decreased with the distance away from the oil well.The rearrangement of physical,physical-chemical and chemical properties of the polluted soils was significant.     

A modified extraction and clean-up procedure for the detection and determination of parathion-methyl and chlorpyrifos residues in tea

Recent advances in methodology and instrumentation have made possible the detection and determination of pesticides at microgram kg-1 (ppb) levels. The sensitivity of a method of analysis depends greatly on the efficient extraction of the pesticide and the subsequent clean-up of the extract. The extract from green tea leaves is a mixture of aroma components, polyphenols and caffeine. The preparation of made tea from green tea leaves adds to this complexity by concentrating these coextractives. Conventional clean-up techniques provide poor recoveries for parathion-methyl and chlorpyrifos from both green tea leaves and made tea. This arises from interference by caffeine during gas chromatography, as it has a similar retention time to the two pesticides and peaks overlap. A modification to the protocol based on a solvent partitioning process using dichloromethane and subsequent washing of the extracts with warm water removed the caffeine, and pigments were removed by column chromatography. Recoveries ranging from 80 to 90% were then obtained for both pesticides.