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Disulfoton, an organophosphorus pesticide, is used to control cotton, beet, potato, and other seedling period aphids, leaf moths, underground pests, etc., with internal absorption, killing, gastric poisoning, and fumigation. Disulfoton is a highly toxic organophosphate pesticide, which can inhibit cholinesterase activity, resulting in neurophysiological disorders by inhalation, feeding, and transdermal absorption. Disulfoton is difficult to degrade in the environment, which leads to enrichment in organisms and interference with endocrine. This compound is harmful to the ecological environment and human health. To ensure the quality and safety of food, it is important to develop a detection method for disulfoton and its metabolites in agricultural products. A reliable method based on dispersive solid phase extraction (d-SPE) with ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for the determination of disulfoton and its metabolites (disulfoton sulfone, disulfoton sulfoxide, demeton

Magnetic restricted-access carbon nanotubes (M-RACNTs) were synthesised and used for dispersive solid phase extraction of organophosphates (chlorpyriphos, malathion, disulfoton, pirimiphos) from commercial bovine raw milk samples. Due to their magnetic susceptibility, M-RACNTs were easily separated from the samples/solvents using a neodymium magnet, and the extracted organophosphates were analysed by gas chromatography-mass spectrometry. The protein exclusion capacity was about 100%. Kinetic and isotherm data (for M-RACNTs – malathion interaction) were adequately adjusted to the pseudo-second order and Sips models, respectively, and the maximum adsorption capacity was about 0.55 mg g-1. The method presented linear ranges from 5.0 to 40.0 μg L-1 for all analytes, with determination coefficients from 0.9902 to 0.9963. The intra-assay precisions (as relative standard deviation) and accuracies (as relative error) ranged from 10.47 to 19.85% and from −0.18 to −18.80%, respectively, whereas the inter-assay precisions ranged from 6.48 to 18.76% and from −0.22 to 19.49%, respectively for 5.0, 20.0 and 40.0 μg L−1 organophosphates levels. The organophosphates were not stable at 4 and 24 h (relative errors ranged from −39.30 to 72.07% and −69.64 to 75.95%, respectively). Limits of detection ranged from 0.36 to 0.95 μg L-1, and 5 μg L-1 was defined as the limit of quantification for all the analytes. The proposed method was applied in the determination of organophosphates in five commercial milk samples, and no pesticides were detected.

Considering the economic importance of the maize crop and the losses caused by the maize stem borer. A research was conducted during the Kharif season 2015 to investigate an infestation of insect pest and evaluating certain granular insecticides as a chemical control method against maize stem borer on maize cultivar BS-1, at the Agricultural, Research Station, Baffa, Mansehra. In this trial, some granular insecticides like Fipronil 0.3G, Furadon 3G, Diazinon 5G, Disulfoton 5G, and Padan were evaluated for the control of maize stem borer and effect on crop production. The results were determined based on the number of the larvae per plant, several dead hearts, and damaged plants per plot. It can be inferred from the obtained data that Padan was the most efficient in reducing the number of larvae Chilo partellus (Swinhoe) (Crambidae: Lepidoptera) (0.11), number of dead heart plants (0.11) and plant damage (0.55) followed Furadon 3G (0.17), (0.18), and (0.89), Diazinon 5G (0.21), (0.37) and (1.32), Fipronil 0.3G (0.24), (0.47) and (1.6), Disulfoton 5G (0.30), (0.66) and (1.95) in descending order as compared to check (0.60), (1.11) and (3.15) respectively. A granular form of insecticides should be preferred the liquid form. Moreover, the granules Padan and Furadon may give better results than the other granular insecticides available in the market.

The matrix effects in bell pepper samples were studied. The simultaneous determination of six organophosphorus (OPPs) pesticides (chlorpyrifos, dichlorvos, disulfoton, ethoprophos, fenchlorphos, an...

Organophosphates are one of the major constituent of herbicides, pesticides, insecticides and nerve gas. Azinophos-methyl, chlorpyrifos, diazinon, fonofos and disulfoton are well-known organophosph...

Aquatic sediments are widely used for the evaluation of anthropogenic contamination due to their ability to adsorb particles and contaminants, making them historical environmental archives. Therefore, the objective was to evaluate the contamination of the Pelotas River sediments, at the border between the states of Santa Catarina and Rio Grande do Sul, by organochlorine and organophosphorus compounds, determining the ecological risk. The evaluation was carried out with quarterly sediment collections in 8 points, totalizing four campaigns within one year, with the aid of the Peterson dredger. Among organochlorines, p'p'DDT stands out regarding environmental persistence, representing 53.23% of the contaminated samples, with values varying up to 0.158 ppb. As for the organophosphates, Methyl Parathion obtained larger representation with 48.4% of the contaminated samples, with concentrations ranging up to 2.42 ppb. The ecological risk of selected organochlorines demonstrated no problems associated with the biota. Regarding the organophosphates studied, Disulfoton presented a risk factor with significant potential for adverse effects on organisms. Therefore, the need for monitoring and sustainability in the use and application of pesticides is well known, aiming at environmental quality and the preservation of natural resources.

The determination of pesticides at trace or ultratrace levels, employing low volumes of organic solvents, in complex and dark colored samples as red and/or rose wines, still represents a challenge in chemical analysis. In this work, we developed a simple and very effective sample preparation procedure based on binary solvent liquid phase microextraction (BS-LPME) for the determination of seventeen multiresidue pesticides in red and rose wines. The extraction device was composed of a 10 mL headspace vial containing a metal crap with a silicone septum and a capillary tube for organic phase collection. The developed procedure was validated and applied in fourteen wine samples. The method showed good linearity (R2 ≥ 0.9987). The limit of detection and limit of quantification ranged from 0.044 μg L−1 (permethrin I) to 0.233 μg L−1 (disulfoton) and from 0.294 μg L−1 (fenitrothion) to 0.777 μg L−1 (disulfoton), respectively. The intraday precision values ranged from 2.9% (ethion) to 16.8% (fenitrothion), whereas the interday precision values were below or equal to 20% for most pesticides. The proposed procedure showed accuracy in the recommended range for complex samples, between 58% (disulfoton) and 121% (molinate), except for parathion and azoxystrobin, due to possible interactions between these compounds and other substances present in the wine matrix. The proposed method showed high sensitivity, which enabled the detection and quantification of low levels of pesticide residues (

Senescence Marker Protein (SMP30) is a metalloenzyme that shows lactonase activity in the ascorbic acid (AA) biosynthesis pathway in non-primate mammals such as a mouse. However, AA biosynthesis does not occur in the primates including humans. Several studies have shown the role of SMP30 in maintaining calcium homeostasis in mammals. In addition, it is also reported to have promiscuous enzyme activity with an organophosphate (OP) substrate. Hence, this study aims to recombinantly express and purify the SMP30 proteins from both mouse and human, and to study their structural alterations and functional deviations in the presence of different divalent metals. For this, mouse SMP30 (MoSMP30) as well as human SMP30 (HuSMP30) were cloned in the bacterial expression vector. Proteins were overexpressed and purified from soluble fractions as well as from inclusion bodies as these proteins were expressed largely in insoluble fractions. The purified proteins were used to study the folding conformations in the presence of different divalent cations (Ca2+, Co2+, Mg2+, and Zn2+) with the help of circular dichroism (CD) spectroscopy. It was observed that both MoSMP30 and HuSMP30 acquired native folding conformations. To study the metal-binding affinity, dissociation constant (Kd values) were calculated from UV-VIS titration curve, which showed the highest affinity of MoSMP30 with Zn2+. However, HuSMP30 showed the highest affinity with Ca2+, suggesting the importance of HuSMP30 in maintaining calcium homeostasis. Enzyme kinetics were performed with γ-Thiobutyrolactone and Demeton-S in the presence of different divalent cations. Interestingly, both the proteins showed lactonase activity in the presence of Ca2+. In addition, MoSMP30 and HuSMP30 also showed lactonase activity in the presence of Co2+ and Zn2+ respectively. Moreover, both the proteins showed OP hydrolase activities in the presence of Ca2+ as well as Zn2+, suggesting the metal-dependent promiscuous nature of SMP30.

Mobility and degradation of the insecticide disulfoton (DST) in the soil were studied in this work, through leaching columns spiked with the analytical standard solution and the commercial product Baysiston ® . In both experiments, the DST presented low mobility, keeping the upper layer of the soil, while its degradation products, mainly the disulfoton sulfone (DSA) and oxygen analogue of disulfoton sulfone (OADSA) percolated into deeper soil layers. Such behavior confirms its potential for contamination of soil and groundwater. It has also been proposed a new DST degradation route wherein oxygen analogue of disulfoton (AODST) can be oxidized to the final degradation product (AODSA) by direct and/or indirect conversion.

An analytical method involving QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation, followed by LC-MS/MS and GC-MS/MS was developed and validated for the determination of 60 pesticides in eggs. Recoveries of 70-120% were achieved for selected pesticides and relative standard deviations20% were obtained for most analytes at three concentrations. The limit of quantification was10 µg kg

The threat of chemical warfare agents (CWA) compels research into novel self-decontaminating materials (SDM) for the continued safety of first-responders, civilians, and active service personnel. The capacity to actively detoxify, as opposed to merely sequester, offending agents under typical environmental conditions defines the added value of SDMs in comparison to traditional adsorptive materials. Porous polymers, synthesized via the high internal phase emulsion (HIPE) templating, provide a facile fabrication method for materials with permeable open cellular structures that may serve in air filtration applications. PolyHIPEs comprising polydicyclopentadiene (polyDCPD) networks form stable hydroperoxide species following activation in air under ambient conditions. The hydroperoxide-containing polyDCPD materials react quickly with CWA simulants, Demeton-S and 2-chloroethyl ethyl sulfide, forming oxidation products as confirmed via gas chromatography mass spectrometry. The simplicity of the detoxification chemistry paired with the porous foam form factor presents an exciting opportunity for the development of self-decontaminating filter media.

This study was performed to determine the storage stability of organophosphorus pesticide residues in high oil content commodity matrices, peanut and soya bean. The storage conditions included different types of solvents (ethyl acetate, acetone and hexane) and corresponding extracted matrix solutions, light and temperature. It was found that three pesticides degraded quickly especially in ethyl acetate solvent. They decreased greater than 30% when stored for 3 days at −20°C in ethyl acetate; the results showed that the stability could be improved in the extracted matrix solutions. Light had a slight effect for stability of phorate and fenthion, while it played an important effect for disulfoton with the exception of ethyl acetate as solvent. Even at −20°C, exposure to solvents or extracted matrix solution resulted in 40.67, 96.33 and 35.07% loss of phorate, disulfoton and fenthion. Hence, it could be assumed that these three residues could be more stable at lower temperature, in the dark and in acetone or hexane extracted peanut and soya bean solutions.

A simple, rapid and sensitive spectrofluorimetric method was developed for the determination of di-syston, ethion and phorate in environmental water samples. The procedure is based on the oxidation of these pesticides with cerium (IV) to produce cerium (III), and its fluorescence was monitored at 368 ± 3 nm after excitation at 257 ± 3 nm. The variables effecting oxidation of each pesticide were studied and optimized. Under the experimental conditions used, the calibration graphs were linear over the range 0.2-15, 0.1-13, 0.1-13 ng mL(-1) for di-syston, ethion and phorate, respectively. The limit of detection and quantification were in the range 0.034-0.096 and 0.112-0.316 ng mL(-1), respectively. Intra- and inter-day assay precisions, expressed as the relative standard deviation (RSD), were lower than 5.2 % and 6.7 %, respectively. Good recoveries in the range 86 %-108 % were obtained for spiked water samples. The proposed method was applied to the determination of studied pesticides in environmental water samples.

Hoewel deze studie een explorerend karakter had, kan geconcludeerd worden dat acute en chronische effecten reeds veroorzaakt kunnen worden door accidentele lozingen van toxische verbindingen bij relatief geringe hoeveelheden. Zo is 10 kg parathion voldoende om ernstige acute effecten te veroorzaken in zoetwater ecosystemen, terwijl een lozing van enkele honderden kg's dieldrin ernstige effecten in de kustwateren en in de kustwateren en de Waddenzee kunnen veroorzaken. Vooral lozingen van specifieke smaak- en geurstoffen kunnen de drinkwaterkwaliteit beinvloeden van oeverinfiltratiewinningen. De algemene conclusie is dat de kwetsbaarheid van de ecosystemen en van de betrokken drinkwatervoorzieningen noopt tot een verdere reductie van het risico dat accidentele lozingen van gevaarlijke verbindingen optreden.

Op basis van de door DBW/RIZA en het RIVM uitgevoerde metingen van de concentraties in Rijnwater van de bij Bazel geloosde bestrijdingsmiddelen zijn schattingen gemaakt van de maximale concentraties van deze stoffen in de Nederlandse oppervlaktewateren. Het betrof met name de stoffen disulfoton en thiometon met maximum concentraties bij Lobith van 2-3 ug/l resp. 8-9 ug/l. In samenhang met de toxiciteitsgegevens moet geconcludeerd worden dat voor de Nederlandse ecosystemen geen schade van dit incident op lange termijn te verwachten is. Overigens is door het ontbreken van inzicht in de exacte toestand van de huidige ecosystemen voor het ongeval herstel van het ecosysteem moeilijk te verifieren. Aanbevolen wordt een biomonitoringsysteem te ontwikkelen zodat bij eventuele toekomstige gevallen de ecologische betekenis beter kan worden aangegeven. De gifgolf kan leiden tot een zekere verslechtering van de kwaliteit van het uit oeverinfiltraat gewonnen drinkwater.

The dissipation/degradation of the pesticides dimethoate, terbufos, disulfoton, and pirimiphos-methyl were evaluated in milled toasted maize and wheat flour (gofio) during three months of storage. Their dissipation kinetics and residual levels were determined, as well as their possible decomposition into some of their main transformation products (disulfoton sulfoxide, terbufos sulfone and disulfoton sulfone). For this purpose, pesticide-free milled toasted maize and wheat samples were spiked with the pesticides, and they were then stored in the darkness at ambient temperature in a closed container to simulate current storage conditions of such packed food. A multiresidue analysis based on the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method was performed for the simultaneous determination of these pesticides and their metabolites. After three months of storage, the dissipation of residues ranged between 34% (pirimiphos-methyl) and 86% (disulfoton) for maize gofio and between 69% (terbufos) and 92% (disulfoton and pirimiphos-methyl) for wheat gofio. The results demonstrated that the degradation was slower in gofio than in wheat gofio and that none of the selected metabolites were detected in any of the samples. Dissipation curves of all studied pesticides fitted to a first-order decay curve in both types of cereals., B.S.R. would like to thank the Canary Agency of Economy, Industry, Trade and Knowledge of the Government of the Canary Islands for the FPI fellowship (co-financed with an 85% from European Social Funds).

This study describes the validation of an analytical method employing gas chromatography with flame photometric detection for the determination of organophosphate pesticides (diazinon, disulfoton, parathion, chlorpyrifos, and malathion) in strawberries. The method employed a QuEChERS dispersive solid phase extraction for the sample preparation. QuEchERS is inexpensive, fast, and easy for the separation of the analytes from the matrix. In addition, the method provided linear calibration curves, ranging from 0.10–1.00 µg g−1, for diazinon, disulfoton, parathion, and chlorpyrifos, and 0.10–2.00 µg g−1 for malathion. Recovery studies yielded values in the range from 81.64 to 100.00%. These results demonstrated the potential of the technique for the determination of organophosphate residues in strawberries.

Two-striped leaf beetle (TSLB) larvae are known to damage soybean root nodules but the effect they have on yield has not been quantitatively assessed. This study was aimed to evaluate the impact of TSLB and to establish a technique to control the larvae. We surveyed 106 farmers’ fields in Aichi prefecture for two years to quantify the changes in TSLB adult population, nodule damage by larvae, and nitrogen (N) content of seeds and stems, growth and yields of soybean plants treated with two different pesticides that were applied to furrow at the time of seeding. The results showed that damage caused by TSLB larval feeding of root nodules was observed particularly in soybeans grown in N-poor soil, and that ureide N content was decreased in plants with damage caused by larval feeding of root nodule, and such damage caused reduction of yield consistently in both years. Furthermore, we also showed the effectiveness of applying insecticides to the sowing furrow at the time of seeding. Specifically, the application of disulfoton to the sowing furrow at a rate of 4 g m–2 as a simple method of pest control limited insect occurrences until the beginning of the blooming stage, curbed the feeding damage to root nodules caused by larvae, and increased the yield of soybean by 20%. This method has been adopted widely in Japan because it can be readily implemented using the fertilization application equipment installed on seeding machines and the insecticide is relatively inexpensive.

The photocatalytic degradation of organophosphorus insecticide disulfoton is investigated by having titanium dioxide (TiO2) as a photocatalyst. About 99% of disulfoton is degraded after UV irradiation for 90 min. The effects of the solution pH, catalyst dosage, light intensity, and inorganic ions on the photocatalytic degradation of disulfoton are also investigated, as well as the reaction intermediates which are formed during the treatment. Eight intermediates have been identified and characterized through a mass spectra analysis, giving insight into the early steps of the degradation process. To the best of our knowledge, this is the first study reporting the degradation pathways of disulfoton. The results suggest that possible transformation pathways may involve in either direct electron or hole transfer to the organic substrate. The photodegradation of disulfoton by UV/TiO2 exhibits pseudo-first-order reaction kinetics and a reaction quantum yield of 0.267. The electrical energy consumption per order of magnitude for photocatalytic degradation of disulfoton is 85 kWh/(m 3 order).

In this manuscript, a dispersive SPE method based on the use of multiwalled carbon nanotubes has been developed for the determination of 15 organophosphorus pesticides residues including some of their metabolites (disulfoton sulfoxide, ethoprophos, cadusafos, dimethoate, terbufos, disulfoton, chlorpyrifos-methyl, malaoxon, fenitrothion, pirimiphos-methyl, malathion, chlorpyrifos, terbufos sulfone, disulfoton sulfone, and fensulfothion) from real environmental waters (run-off, mineral and tap water) by GC with nitrogen phosphorus detection. Factors that affect the enrichment efficiency such as sample volume, multiwalled carbon nanotubes amount, and volume of eluent were studied. The optimized method was validated in terms of matrix-matched calibration, recovery, precision, and accuracy for the three analyzed samples. In this last case, the developed Student's t test demonstrated that there were no significant differences between real and spiked concentrations. Optimum dispersive SPE conditions (extraction of 200 mL of water, pH 6.0, with 130 mg of multiwalled carbon nanotubes, elution with 25 mL of dichloromethane for run-off and tap water and 30 mL for mineral water) allowed the quantitative extraction of analytes at levels lower than the maximum residues limits legislated by the European Union, with LODs between 1.16 and 93.6 ng/L. Absolute recovery values achieved were in the range of 67-107% (RSD values

The residue levels of organochlorine (OCP) and organophosphorus (OPP) in some dairy products and baby foods samples in Assiut markets Egypt were determined. The concentrations of OCP and OPP were determined in milk powder, plain yoghurt, fruit yoghurt, breakfast cereals, wheat cereal-based baby foods, rice cereal-based baby foods and vegetables and fruit-based baby foods by gas chromatography/mass spectrometry. In dairy products, the highest values of OCP and OPP were 9.346 ± 0.950 μg/kg methoxychlor in fruit yoghurt and 2.282 ± 0.400 μg/kg disulfoton in plain yoghurt, respectively. Propachlor, dieldrin (OCP), chlorpyrifos, and parathion- methyl (OPP) were not detected in any dairy product samples. Maximum amounts of methoxychlor (12.710 ± 0.700 μg/kg) and disulfoton (5.369 ± 0.510 μg/kg) were recorded in vegetables and fruit-based baby foods, and wheat cereal-based baby foods, respectively. The analysis of dairy products and baby foods showed lower pesticides values than the permissible limit set by the European Commission in all products, except methoxychlor (OCP) in vegetables and fruit-based baby foods. The results will help in a scientific assessment of the implications of pesticide residues with regards to human risks in Egypt.

The effects of a five-pesticide mixture on pesticide accumulation, phytohormone levels (indole-3-acetic acid, gibberellic acid, jasmonic acid, and salicylic acid), pigment contents (total chlorophyll and carotenoid), antioxidant enzyme (catalase and guaiacol peroxidase) activities, lipid peroxidation product (malondialdehyde), and DNA profiles were investigated in the leaves of Veronica beccabunga. Laboratory-acclimatized plants were treated with a mix of five pesticides (atrazine, disulfoton, chlorpyrifos, metalaxyl, and ethion) in doses of 50 ppt, 1 ppb, 100 ppb, and 1 ppm for 1, 3, and 6 days. The accumulation of each pesticide, from highest to lowest, was as follows: chlorpyrifos, atrazine, metalaxyl, disulfoton, and ethion. The amounts of total chlorophyll and protein decreased with increased pesticide concentration. Antioxidant enzyme activities and malondialdehyde amount increased linearly with increasing pesticide exposure. However, the highest pesticide concentration caused decreases in guaiacol peroxidase (POD) activity and malondialdehyde (MDA) content at all treatment times. Both jasmonic and salicylic acid levels increased with pesticide exposure and decreased gradually after. It was also determined that application of the pesticide mixture affected the DNA profiles of V. beccabunga. The most band changes were detected on the sixth day of treatment., T.R. State Planning Organization [2010K120440], The author is grateful to Prof. Dr. Irfan ASLAN (Rector of Agri Ibrahim Cecen University, Agri/Turkey) and Agri Central Research and Application Laboratory which is funded by T.R. State Planning Organization (Project Number: 2010K120440) for providing laboratory equipment and financial support for this research. The author also wisher to thank Assoc. Prof. Dr. Oguzhan Doganlar (Agri Ibrahim Cecen University, Agri, Turkey) for performing statistical analysis and Prof. Dr. Anne Frary (Izmir Institute of Technology, Izmir Turkey) for extensive proofreading of the manuscript

Analytical potentiality of a modified version of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method has been studied and validated for the extraction of a group of 11 pesticides (ethoprophos, cadusafos, dimethoate, terbufos, disulfoton, chlorpyrifos-methyl, fenitrothion, pirimiphos-methyl, malathion, chlorpyrifos and fensulfothion) and some of their metabolites (malaoxon, disulfoton sulfoxide, terbufos sulfone and disulfoton sulfone) in toasted barley and chickpea flours. The method involves separation and quantification by gas chromatography (GC) with nitrogen phosphorus detection (NPD) using triphenylphosphate as the internal standard. Matrix-matched calibration was carried out for both flours due to the existence of a matrix effect. Linearity, recovery, precision and accuracy studies of the proposed QuEChERS-GC-NPD method were evaluated in each sample matrix. Mean recovery values were in the range of 73-118% with relative standard deviation values below 10%. Limits of detection of the whole method were between 0.07 and 57.39 μg/kg. The method was finally applied for the analysis of 14 samples collected in different zones of the Tenerife island. The residues of pirimiphos-methyl were found in 13 of them, confirming its unequivocal presence by mass spectrometry.

An analytical method using solid phase extraction (SPE) and analysis by gas chromatography/mass spectrometry (GC–MS) was developed to determine trace levels of a variety of 41 agricultural pesticides and selected transformation products in high-elevation surface waters. Large-volume water sampling (up to 100 L) was employed because it was anticipated that pesticide contamination, if present, would be at very low levels. The target compounds comprise pesticides (and selected oxygen transformation products) known to have been extensively used in agriculture in the San Joaquin Valley, CA, USA. Solid phase extraction using the polymeric resin Abselut Nexus was optimized to extract the pesticide analytes from water samples. A single determinative method using GC–MS with electron ionization was used for all the analytes. Recoveries from 100 L of reagent water at 100 pg/L and 1 ng/L concentrations were generally greater than 75%, although dimethoate, disulfoton, and phorate were not recovered. Analysis of the extracts without cleanup yielded detection limits for the remaining 38 analytes between 0.1 and 30 ng/L. A silica cleanup with separate analysis of 3 eluant fractions improved detection limits for 37 of the compounds to between 6 and 600 pg/L in high-elevation surface waters.

The behavior of several pesticides in aqueous solution, namely bifenthrin, amethrin (pyrethroid insecticides), endosulfan and endosulfan sulfate (organochlorine pesticides), disulfoton, methyl pyrimiphos, and phorate (organophosphorus pesticides), submitted to the conditions typically employed in water treatment stations was investigated. Continuous pesticide depletion was monitored by solid-phase microextraction sampling followed by gas chromatography–mass spectrometry analysis. The influence of major parameters (sodium hypochloride concentration, solution pH, and exposure time to ultraviolet (UV) light) was, thus, adequately established via two complementary approaches: factorial (23, three variables—two levels) and Doehlert designs. Hence, the sodium hypochloride concentration and the solution pH produced distinct effects depending on the pesticide evaluated (for instance, acidic and basic media caused increasing rates of degradation for the organophosphorus/pyrethroid and organochlorine pesticides, respectively). Conversely, higher rates of degradation were achieved for all of the pesticides investigated when increased exposure times to UV radiation were employed. Finally, the exposure time to UV radiation that lead to complete degradation of disulfoton and endosulfan sulfate (organophosphorus and organochlorine pesticides, respectively) in aqueous media under ordinary conditions employed in water treatment stations was established; disulfoton and endosulfan sulfate were completely degraded after 10 and 40 h, respectively.

Ten organophosphate (OP) pesticides: phorate, disulfoton, terbufos, methidathion, bensulide, chlorethoxyfos, phosmet, methyl parathion, phostebupirim, and temephos were evaluated for their potential to undergo oxidation to their respective oxons and/or other oxidation analogues in laboratory water. Samples were collected at time intervals up to 72h of chlorination and analyzed by both gas chromatography-mass selective detection (GC-MSD) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The results show that methidathion and methyl parathion were stable in unchlorinated water, while all other OP pesticides were not stable over the 72h exposure period. In chlorinated water, phorate and disulfoton formed stable sulfone oxons. Temephos formed stable dioxon sulfoxide and dioxon sulfone. Methidathion, bensulide, chlorethyoxyfos, methyl parathion, and phostebupirim formed stable oxons over the 72h exposure period. Terbufos, phorate, disulfoton and temephos oxon sulfoxides; temephos sulfoxide; and phosmet oxon were initially formed but were not detected after 24h. The data illustrate that organothiophosphate pesticides may form oxons and/or other oxidation analogues during chlorination in water treatment plants, which are persistent for at least 72h.

The monitoring of pesticides in Colombian foods is limited and poorly implemented. Moreover, producers tend to use pesticides in excess, mainly for economic reasons. In this study the presence of the organophosphate pesticides chlorpiryfos, profenofos, disulfoton, methyl parathion, ethion and malathion was determined in the foods; tomatoes, onions, potatoes, grapes, strawberries and apples produced in Colombia using a multi-residue method. Following this, samples acquired in the local market of Bucaramanga were analyzed. In all samples (n=35) residues from at least two organophosphate pesticides were found (6% of the samples contained residues of 2 pesticides, 17% of 3, 20% of 4, 46% of 5 and 11% of 6). For the profenofos pesticide, the MRL (Maximum Residual Limit) was exceeded in more of 50% of the samples. &nbsp, En Colombia el diagnostico, la vigilancia y el monitoreo de plaguicidas en alimentos aún no se ha implementado de forma eficaz, y existe una tendencia fuerte de los agricultores a usar plaguicidas en forma excesiva, especialmente por motivaciones económicas. En este trabajo se presenta la determinación de los plaguicidas organofosforados: clorpirifos, diazinon, disulfotón, metil paratión, malatión, profenofos, y etión, en muestras de: papa, cebolla, tomate, manzana, fresas y uvas; con el fin de conocer los niveles residuales de estos plaguicidas en vegetales producidos y consumidos en Colombia, mediante la implementación de un método multiresiduo con posterior análisis de muestras adquiridas en el mercado local de Bucaramanga, Colombia. En dicha determinación, se observó que el total de las muestras analizadas (35), contiene residuos de más de dos plaguicidas organofosforados (el 6 % de las muestras contiene residuos de 2 plaguicidas, el 17 % de 3, el 20 % de 4, el 46% de 5 y el 11 % de 6); además para el plaguicida profenofos se excede el MRL (Limite Máximo Residual) en más del 50 % de los casos. &nbsp

BACKGROUND: Late watergrass [Echinochloa phyllopogon (Stapf.) Koss.] is a major weed of Californian rice that has evolved P450-mediated metabolic resistance to multiple herbicides. Resistant (R) populations are also poorly controlled by the recently introduced herbicide clomazone. The authors assessed whether this cross-resistance was also P450 mediated, and whether R plants also had reduced sensitivity to photooxidation. Understanding mechanism(s) of resistance facilitates the design of herbicide management strategies to delay resistance evolution. RESULTS Ratios (R/S) of R to susceptible (S) GR50 were near 2.0. [14C]Clomazone uptake was similar in R and S plants. Clomazone and its metabolite 5-ketoclomazone reduced chlorophyll and carotenoids in S more than in R plants. The P450 inhibitors disulfoton and 1-aminobenzo-triazole (ABT) safened clomazone in R and S plants. Disulfoton safened 5-ketoclomazone only in S plants, while ABT synergized 5-ketoclomazone mostly against S plants. Paraquat was more toxic in S than in R plants. CONCLUSION: Cross-resistance to clomazone explains failures to control R plants in rice fields, and safening by P450 inhibitors suggests that oxidative activation of clomazone is needed for toxicity to E. phyllopogon. Clomazone resistance requires mitigation of 5-ketoclomazone toxicity, but P450 detoxification may not significantly confer resistance, as P450 inhibitors poorly synergized 5-ketoclopmazone in R plants. Responses to paraquat suggest research on mechanisms to mitigate photooxidation in R and S plants is needed. Copyright © 2008 Society of Chemical Industry

There is considerable concern regarding the biological plausibility of the response of certain chemicals in the in vitro photoclastogenicity assay, suggesting that this assay is oversensitive and lacks specificity. To explore this further, four coded compounds (aminotriazole, propantheline bromide, cycloheximide and disulfoton) were evaluated for their potential response in a photoclastogenicity assay in cultured Chinese hamster ovary (CHO) cells. None of the four compounds were shown to absorb ultraviolet radiation (UVR) or visible light in the 290- to 700-nm region of the electromagnetic spectrum. A fifth coded compound, tetracycline, which absorbs UVR, was also tested as this has previously been shown to be phototoxic in vitro (3T3-NRU assay) and is cytotoxic, but not genotoxic, at high concentrations in standard 'dark' genotoxicity assays in mammalian cells. The results showed that cycloheximide, disulfoton and tetracycline were clastogenic in CHO cells following UVR exposure (solar-simulated light at 700 mJ/cm(2)) but not in the absence of UVR. Aminotriazole and propantheline were negative in the presence and absence of UVR exposure. Follow-up testing showed that neither cycloheximide nor disulfoton was positive in the 3T3-NRU assay, the standard in vitro regulatory test for phototoxicity, a result consistent with their inability to absorb UVR. These data suggest that both cycloheximide and disulfoton are pseudophotoclastogens, like zinc oxide. Together, these data question the specificity of the in vitro photoclastogencity assay in CHO cells and raises further concern regarding its use for the assessment of chemical photosafety for regulatory purposes. At the very least, a review of the current guidance documents for the photosafety evaluation of pharmaceuticals and cosmetics should be undertaken urgently.

A simple and efficient binary solvent-based two-phase hollow fiber membrane (HFM)-protected liquid-phase microextraction (BN-LPME) technique for moderately polar compounds was developed. Six organophosphorous pesticides (OPPs) (triethylphosphorothioate, thionazin, sulfotep, phorate, disulfoton, methyl parathion and ethyl parathion) were used as model compounds and extracted from 10-mL wastewater with a binary-solvent (toluene:hexane, 1:1) mixture. Some important extraction parameters, such as extraction time, effect of salt, sample pH and solvent ratio composition were optimized. BN-LPME combined with gas chromatography/mass spectrometric (GC/MS) analysis provided repeatability (R.S.D.sor = 12%, n = 4), and linearity (ror = 0.994) and solid-phase microextraction provides comparable of R.S.D.sor = 13%, n = 4 and linearity (ror = 0.966) for spiked water samples. The limits of detection (LODs) were in the range of 0.3-11.4 ng L(-1) for BN-LPME and 3.1-120.5 ng L(-1) for SPME at (S/N = 3) under GC/MS selective ion monitoring mode. In addition to high enrichment, BN-LPME also served as a sample cleanup procedure, with the HFM act as a filtering medium to prevent large particles and extraneous materials from being extracted. To investigate and compare their applicability, the BN-LPME and SPME procedures were applied to the detection of OPPs in domestic wastewater samples.

Glycerophosphodiesterase (GpdQ) from Enterobacter aerogenes is a nonspecific diesterase that enables Escherichia coli to utilize alkyl phosphodiesters, such as diethyl phosphate, as the sole phosphorus source. The catalytic properties of GpdQ were determined, and the best substrate found was bis(p-nitrophenyl) phosphate with a kcat/Km value of 6.7 x 10(3) M-1 s-1. In addition, the E. aerogenes diesterase was tested as a catalyst for the hydrolysis of a series of phosphonate monoesters which are the hydrolysis products of the highly toxic organophosphonate nerve agents sarin, soman, GF, VX, and rVX. Among the phosphonate monoesters tested, the hydrolysis product of rVX, isobutyl methyl phosphonate, was the best substrate with a kcat/Km value of 33 M-1 s-1. The ability of GpdQ to hydrolyze the phosphonate monoesters provides an alternative selection strategy in the search of enhanced variants of the bacterial phosphotriesterase (PTE) for the hydrolysis of organophosphonate nerve agents. This investigation demonstrated that the previously reported activity of GpdQ toward the hydrolysis of methyl demeton-S is due to the presence of a diester contaminant in the commercial material. Furthermore, it was shown that GpdQ is capable of hydrolyzing a close analogue of EA 2192, the most toxic and persistent degradation product of the nerve agent VX.