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Journal of Chromatographic Science Mar 2010Determination of 23 organophosphorous pesticides (sulfotep, phorate, demeton, diazinon, disulfoton, kitazzin.P, chlorpyrifos-methyl, methyl-parathion, ronnel,...
Determination of 23 organophosphorous pesticides (sulfotep, phorate, demeton, diazinon, disulfoton, kitazzin.P, chlorpyrifos-methyl, methyl-parathion, ronnel, fenitrothion, malathion, chlorpyrifos, fenthion, parathion, bromophos, isofenphos-methyl, phenthoate, quinalphos, ethion, triazophos, carbophenothion, pirimiphos-methyl, and pirimiphos-ethyl) in water using solid-phase microextraction (SPME) with gas chromatography-mass spectrometry detection (GC-MS) was investigated. The influence of various parameters on pesticides extraction efficiency by SPME was thoroughly studied. For quantitation in the selective ion monitoring (SIM) mode, the linear range of most compounds was found to be between 0.05-10 microg/L, and the detection limits were between 0.7-50 ng/L. To validate matrix effects for surface water, the recoveries were calculated between 71-104%. SPME in combination with GC-MS is a sensitive and effective method for the determination of organophosphorous pesticides (OPPs) in water samples.
Topics: Gas Chromatography-Mass Spectrometry; Limit of Detection; Organothiophosphorus Compounds; Pesticides; Rivers; Solid Phase Microextraction; Water; Water Pollutants, Chemical
PubMed: 20223083
DOI: 10.1093/chromsci/48.3.183 -
Journal of Agricultural and Food... Jan 2010Air samples were collected continuously in Egbert, Ontario, which is in a rural agricultural area north of Toronto, between March 2006 and September 2007 and analyzed...
Air samples were collected continuously in Egbert, Ontario, which is in a rural agricultural area north of Toronto, between March 2006 and September 2007 and analyzed for pesticides of both current and historic use. The fungicide chlorothalonil was present in highest abundance with levels exceeding 2000 pg x m(-3) in the summer. Almost as abundant, with summer time concentrations around 400 to 600 pg x m(-3), were the herbicides atrazine, alachlor, and metolachlor. Other pesticides in current use, such as trifluralin, pendimethalin, chlorpyrifos, endosulfan, and disulfoton were consistently present at levels approximately 1 order of magnitude lower. Concentrations of banned pesticides (chlordanes and hexachlorocyclohexane) were generally below 10 pg x m(-3), except for hexachlorobenzene, which was present at the global average of approximately 50 pg x m(-3). These levels and the fact that they are generally lower than what has been reported for the area previously are in agreement with pesticide usage data for Ontario. Only the concentrations of chlorothalonil, chlorpyrifos, and HCB were correlated with air mass origin, as determined by back trajectory analysis. All pesticides had higher levels during the growing season compared to those in winter, but the ratio of concentrations during the different seasons is much higher for the pesticides in current use. That ratio may aid in distinguishing seasonal variability caused by pesticide application during the growing season from that caused by temperature-driven revolatilization. Higher concentrations of the banned pesticides during 2007 compared to those in 2006 may be due to higher volatilization rates caused by higher surface temperatures consistent with the El Nino Southern Oscillation.
Topics: Air Pollutants; Nitriles; Ontario; Pesticides; Seasons
PubMed: 20039708
DOI: 10.1021/jf902898f -
Water Research Feb 2009Ten organophosphate (OP) pesticides: phorate, disulfoton, terbufos, methidathion, bensulide, chlorethoxyfos, phosmet, methyl parathion, phostebupirim, and temephos were...
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.
Topics: Halogenation; Insecticides; Molecular Structure; Organophosphorus Compounds; Organothiophosphates; Oxidation-Reduction; Water Pollutants, Chemical; Water Purification; Water Supply
PubMed: 19027135
DOI: 10.1016/j.watres.2008.10.038 -
Talanta May 2006A technique for the analysis of organophosphorus pesticides (ethoprop, diazinon, disulfoton, fenthion) in aqueous sample using liquid-phase microextraction (LPME),...
Determination of ethoprop, diazinon, disulfoton and fenthion using dynamic hollow fiber-protected liquid-phase microextraction coupled with gas chromatography-mass spectrometry.
A technique for the analysis of organophosphorus pesticides (ethoprop, diazinon, disulfoton, fenthion) in aqueous sample using liquid-phase microextraction (LPME), coupled with gas chromatography-mass spectrometry (GC-MS) was developed. A small section of a hollow fiber inserted into the needle of GC syringe and filled with the 3.5mul of organic solvent was used to extract pesticides from a 20ml aqueous sample. The limits of detection (LOD) with the selected ion monitoring (SIM) mode varied from 0.2 to 0.006mug/l. The calibration curves were linear over three orders of magnitude with R(2)>/=0.996. The relative standard deviations of the analysis (inter- and intra-day) were 5-8%, and the relative recoveries from the lake water sample were greater than 83%. The results were compared with results obtained using solid-phase microextraction (SPME/GC/MS).
PubMed: 18970620
DOI: 10.1016/j.talanta.2005.10.042 -
Pest Management Science Oct 2008Late watergrass [Echinochloa phyllopogon (Stapf.) Koss.] is a major weed of Californian rice that has evolved P450-mediated metabolic resistance to multiple herbicides....
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) GR(50) were near 2.0. [(14)C]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.
Topics: Biomass; California; Cytochrome P-450 Enzyme Inhibitors; Cytochrome P-450 Enzyme System; Disulfoton; Echinochloa; Enzyme Inhibitors; Herbicide Resistance; Herbicides; Isoxazoles; Oryza; Oxazolidinones; Paraquat; Pigments, Biological
PubMed: 18493924
DOI: 10.1002/ps.1604 -
Mutagenesis Mar 2008There is considerable concern regarding the biological plausibility of the response of certain chemicals in the in vitro photoclastogenicity assay, suggesting that this... (Comparative Study)
Comparative Study
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.
Topics: Amitrole; Animals; CHO Cells; Chromosome Aberrations; Cricetinae; Cricetulus; Cycloheximide; DNA Damage; Disulfoton; Mutagenicity Tests; Mutagens; Propantheline; Tetracycline; Ultraviolet Rays
PubMed: 18227081
DOI: 10.1093/mutage/gem053 -
Analytica Chimica Acta Dec 2007A simple and efficient binary solvent-based two-phase hollow fiber membrane (HFM)-protected liquid-phase microextraction (BN-LPME) technique for moderately polar... (Comparative Study)
Comparative Study
Determination of organophosphorous pesticides in wastewater samples using binary-solvent liquid-phase microextraction and solid-phase microextraction: a comparative study.
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.s < or = 12%, n = 4), and linearity (r < or = 0.994) and solid-phase microextraction provides comparable of R.S.D.s < or = 13%, n = 4 and linearity (r < or = 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.
Topics: Chemistry Techniques, Analytical; Disulfoton; Gas Chromatography-Mass Spectrometry; Herbicides; Methyl Parathion; Organophosphorus Compounds; Organothiophosphates; Organothiophosphorus Compounds; Parathion; Pesticide Residues; Phorate; Reproducibility of Results; Solid Phase Microextraction; Solvents; Water Pollutants, Chemical; Water Purification
PubMed: 18036377
DOI: 10.1016/j.aca.2007.10.006 -
Food Additives and Contaminants Nov 2007An evaluation of the stability of pesticides in fruit and vegetables during cryogenic sample processing (comminution of samples in the presence of dry ice) is reported....
An evaluation of the stability of pesticides in fruit and vegetables during cryogenic sample processing (comminution of samples in the presence of dry ice) is reported. Pesticides were spiked onto the undamaged surface of individual units of fruit before freezing and comminution. The mean recoveries of pesticides spiked before and after comminution of the sample were compared to determine the relative stability of the individual pesticides during cryogenic sample processing. A stable internal deposition standard (IDS) was used to correct for physical losses and volumetric errors. Mean recovery results together with associated standard errors were obtained using restricted maximum likelihood (REML) analysis. A total of 134 pesticides in four commodities (apples, grapes, lettuce and oranges) were evaluated. The results demonstrated that 120 pesticides were stable (i.e. the mean difference in recovery of pesticides spiked pre- and post-processing was <20%) during cryogenic sample processing. Fourteen pesticides showed some instability or loss (i.e. the mean difference in recovery of pesticides spiked pre- and post-processing was >20%) during cryogenic sample processing: biphenyl, cadusafos, captan, chlorothalonil, dichlorvos, disulfoton, ethoxyquin, etridiazole, heptenophos, malaoxon, phorate, tebuconazole, tecnazene and trifluralin.
Topics: Chromatography, Gas; Drug Stability; Food Analysis; Food Contamination; Food Handling; Freezing; Fruit; Pesticide Residues; Reproducibility of Results; Tandem Mass Spectrometry; Vegetables
PubMed: 17852403
DOI: 10.1080/02652030701317319 -
Journal of Economic Entomology Aug 2007The linden borer, Saperda vestita Say (Coleoptera: Cerambycidae), is a native insect species that is common throughout north central and northeastern North America. Over...
The linden borer, Saperda vestita Say (Coleoptera: Cerambycidae), is a native insect species that is common throughout north central and northeastern North America. Over the past decade, increasing occurrence of damage associated with the linden borer has been reported on Tilia spp. in city street trees and nurseries throughout Wisconsin, probably because of increased use of these trees. Our objective was to gain a better understanding of the seasonal biology and potential management strategies for this important pest. We evaluated the effectiveness of three systemic insecticides, imidacloprid, thiamethoxam, and disulfoton, and a mechanical control method of chipping linden borer-infested wood as a means of reducing S. vestita larval survival, subsequent emergence, and oviposition. Autumn and spring soil injections of imidacloprid to linden borer-infested Tilia cordata'Greenspire' nursery stock (< 11.4 cm in diameter at breast height [dbh]) provided >90% control. Autumn soil injections of imidacloprid and thiamethoxam and a spring granular soil application treatment of disulfoton applied to larger (>22 cm dbh) Tilia spp. did not effectively control linden borer at the application rates tested. Chipping infested Tilia spp. effectively destroyed linden borer larvae, pupae, and adults. Arborists and landscape managers should consider chipping felled Tilia spp. trees infested with S. vestita to prevent adults from potentially attacking nearby susceptible trees.
Topics: Animals; Coleoptera; Disulfoton; Imidazoles; Insect Control; Insecticides; Larva; Neonicotinoids; Nitro Compounds; Oxazines; Pupa; Seasons; Thiamethoxam; Thiazoles; Tilia; Wisconsin
PubMed: 17849886
DOI: 10.1603/0022-0493(2007)100[1328:pmsftl]2.0.co;2 -
Se Pu = Chinese Journal of... May 2007A method for the determination of organic phosphorus pesticide residues is described. It covers 25 residues in scallion including dichlorvos, ethoprophos, phorate,...
A method for the determination of organic phosphorus pesticide residues is described. It covers 25 residues in scallion including dichlorvos, ethoprophos, phorate, diazinon, disulfoton, dimethoate, pirimiphos-methyl, chlorpyrifos, malathion, fenitrothion, parathion, chlorfenvinphos, ethion, EPN, dyfonate, chlorpyrifos-methyl, parathion-methyl, fenthion, quinalphos, gardona, methidathion, carbophenothion, phosmet, phosalone, and coumaphos. After the scallion samples were heated for 30 s in microwave oven, the residues were extracted with acetonitrile, and then the organic phase was salted out from the matrix. As a result, most of the interfering impurities were abolished in the heating process. In this study, these pesticides were categorized into two groups for analysis. The gas chromatographic analysis was performed on a capillary column (DB-1701, 30 m x 0.25 mm x 0.25 microm) and determined with a flame photometric detector. Linear correlation coefficients of the 25 organic phosphorus pesticides were not lower than 0.991 0 and the linear ranges for most of the compounds were between 0.1 to 5.0 mg/L. The detection limits were between 0.025 and 0.200 mg/L. In recovery study, average recoveries ranged from 85.2% to 119.6% at the fortification levels of 0.05, 0.2 and 0.5 mg/kg and the relative standard deviations were in the range of 2.1% and 14.8%. The method is a simple, rapid and highly efficient one to determine organic phosphorus pesticide residues in scallion.
PubMed: 17679438
DOI: No ID Found