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Food Chemistry Nov 2019An 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...
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 deviations <20% were obtained for most analytes at three concentrations. The limit of quantification was <10 µg kg for 83% of the total pesticides. This method was used to analyze 58 egg samples and the residues of seven pesticides (disulfoton, fipronil sulfone, cyromazine, o,p-DDT, p,p-DDD, p,p-DDT, and permethrin) were quantified in 16 egg samples at levels of 5-10 µg kg, which was below the corresponding the maximum residue levels, as established by Korean Ministry of Food and Drug Safety. We demonstrated that LC-MS/MS and GC-MS/MS in combination with QuEChERS can be used to routinely monitor multiple pesticide residues in egg samples.
Topics: Animals; Chickens; Chromatography, High Pressure Liquid; Disulfoton; Eggs; Female; Gas Chromatography-Mass Spectrometry; Limit of Detection; Pesticide Residues; Pyrazoles; Reproducibility of Results; Tandem Mass Spectrometry
PubMed: 31260955
DOI: 10.1016/j.foodchem.2019.125050 -
Toxicology and Applied Pharmacology Oct 1983Tolerance to the toxic signs of the organophosphorus ester acetylcholinesterase inhibitor, O,O-diethyl S-[2-(ethylthio)ethyl] phosphorodithioate (disulfoton), was...
Tolerance to the toxic signs of the organophosphorus ester acetylcholinesterase inhibitor, O,O-diethyl S-[2-(ethylthio)ethyl] phosphorodithioate (disulfoton), was induced in rats by giving 10 doses of 2.0 mg/kg/day. Concurrent with the induction of tolerance, decreased sensitivity to the cholinergic agonists carbachol and oxotremorine could be demonstrated in studies of heart rate in vivo and in isolated preparations of ileum and atria. A significant decrease in the binding of the muscarinic antagonist [3H]quinuclidinyl benzilate could be demonstrated in ileum from disulfoton-tolerant animals. However, no alterations in the binding of [3H]quinuclidinyl benzilate, [3H]oxotremorine-M, or oxotremorine were evident in atria from tolerant animals. The results suggest that, in addition to receptor loss, other mechanisms distal to ligand recognition sites or removed from the receptor complex may contribute to the subsensitivity of tissues to muscarinic cholinergic agonists.
Topics: Animals; Cholinesterase Inhibitors; Disulfoton; Drug Tolerance; Heart Rate; In Vitro Techniques; Male; Oxotremorine; Quinuclidinyl Benzilate; Rats; Rats, Inbred Strains; Receptors, Muscarinic
PubMed: 6636179
DOI: 10.1016/0041-008x(83)90041-8 -
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 -
Chemosphere Aug 2014The interaction mechanisms of catalase (CAT) with pesticides (including organophosphates: disulfoton, isofenphos-methyl, malathion, isocarbophos, dimethoate, dipterex,...
The interaction mechanisms of catalase (CAT) with pesticides (including organophosphates: disulfoton, isofenphos-methyl, malathion, isocarbophos, dimethoate, dipterex, methamidophos and acephate; carbamates: carbaryl and methomyl; pyrethroids: fenvalerate and deltamethrin) were first investigated by flow injection (FI) chemiluminescence (CL) analysis and molecular docking. By homemade FI-CL model of lg[(I0-I)/I]=lgK+nlg[D], it was found that the binding processes of pesticides to CAT were spontaneous with the apparent binding constants K of 10(3)-10(5) L mol(-1) and the numbers of binding sites about 1.0. The binding abilities of pesticides to CAT followed the order: fenvalerate>deltamethrin>disulfoton>isofenphos-methyl>carbaryl>malathion>isocarbophos>dimethoate>dipterex>acephate>methomyl>methamidophos, which was generally similar to the order of determination sensitivity of pesticides. The thermodynamic parameters revealed that CAT bound with hydrophobic pesticides by hydrophobic interaction force, and with hydrophilic pesticides by hydrogen bond and van der Waals force. The pesticides to CAT molecular docking study showed that pesticides could enter into the cavity locating among the four subdomains of CAT, giving the specific amino acid residues and hydrogen bonds involved in CAT-pesticides interaction. It was also found that the lgK values of pesticides to CAT increased regularly with increasing lgP, Mr, MR and MV, suggesting that the hydrophobicity and steric property of pesticide played essential roles in its binding to CAT.
Topics: Animals; Catalase; Cattle; Flow Injection Analysis; Luminescence; Luminescent Measurements; Molecular Docking Simulation; Pesticides; Protein Binding; Thermodynamics
PubMed: 24875908
DOI: 10.1016/j.chemosphere.2014.02.075 -
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 -
The Journal of Pharmacology and... Aug 1983(+/-)-[3H]Nicotine binds specifically to rat brain membranes. The binding is stereospecific, (+)-nicotine being 57 times less potent than (-)-nicotine in displacing...
(+/-)-[3H]Nicotine binds specifically to rat brain membranes. The binding is stereospecific, (+)-nicotine being 57 times less potent than (-)-nicotine in displacing labeled (+/-)-nicotine. Saturation binding experiments revealed the presence of two binding sites with dissociation constant (Kd) values of 23.7 and 590 nM, and binding site density (Bmax) values of 76 and 646 fmol/mg of protein, respectively. The substrate specificity of the binding site suggests that it represents the nicotinic cholinergic receptor. [3H] Nicotine binding was found to be highest in the hypothalamus and hippocampus and lowest in the cerebellum. Chronic treatment with the acetylcholinesterase inhibitor disulfoton (2 mg/kg/day for 10 days) decreased the number of cholinergic muscarinic and nicotinic binding sites in rat brain. Moreover, the antinociceptive effect of nicotine was found to be markedly reduced in rats chronically treated with disulfoton.
Topics: Acetylcholinesterase; Analgesia; Animals; Binding Sites; Brain; Cholinesterase Inhibitors; Disulfoton; Male; Nicotine; Quinuclidinyl Benzilate; Rats; Rats, Inbred Strains
PubMed: 6875853
DOI: No ID Found -
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 -
Food Additives and Contaminants Jul 2007A survey was carried out to assess the levels of 20 organochlorine and 15 organophosphate pesticides in wheat grown in two regions of the Vojvodina Province in Serbia. A...
A survey was carried out to assess the levels of 20 organochlorine and 15 organophosphate pesticides in wheat grown in two regions of the Vojvodina Province in Serbia. A total of 49 samples of seven wheat varieties were collected during the 2004 harvest. In addition, a composite sample of cultivated wheat varieties was prepared from 36 samples coming from the same regions harvested in 2003 for comparison. Official method of analysis AOAC 970.52 was applied for the determination of pesticide residues. The ranges of mean values for organochlorine residues were 32-47 ng g(-1) for beta-HCH; 28-41 ng g(-1) for gamma-HCH; <1-61 ng g(-1) for aldrin; 5-132 ng g(-1) for dieldrin; 15-111 ng g(-1) for endrin ketone; and <1-77 ng g(-1) for endrin aldehyde. For organophosphate residues the ranges were: 7-27 ng g(-1) for thionazin; <5-35 ng g(-1) for disulphoton; 42-79 ng g(-1) for parathion methyl; 422-1336 ng g(-1) for chlorpyriphos; and <5-281 ng g(-1) for parathion. The mean levels of residues were compared with the regulated maximum levels according to the European Commission and Serbian national regulation, and the average intake of residues from wheat-based products was estimated for the Serbian population.
Topics: Edible Grain; Food Analysis; Food Contamination; Gas Chromatography-Mass Spectrometry; Hydrocarbons, Chlorinated; Organophosphates; Pesticide Residues; Yugoslavia
PubMed: 17613054
DOI: 10.1080/02652030601182888 -
Drug Metabolism and Disposition: the... Mar 2004Cytochrome P450 (P450) and flavin-containing monooxygenase (FMO) enzymes are major catalysts involved in the metabolism of xenobiotics. The sulfoxidation of the...
Cytochrome P450 (P450) and flavin-containing monooxygenase (FMO) enzymes are major catalysts involved in the metabolism of xenobiotics. The sulfoxidation of the thioether pesticides, phorate, disulfoton, sulprofos, and methiocarb, was investigated. Using pooled human liver microsomes (HLMs), thioether compounds displayed similar affinities; however, phorate and disulfoton displayed higher intrinsic clearance rates than either sulprofos or methiocarb. The sulfoxidation of thioethers by HLMs was found to be predominantly P450-driven (85-90%) compared with FMO (10-15%). Among 16 cDNA-expressed human P450 isoforms and 3 human FMO isoforms examined, the following isoforms and their polymorphisms had the highest rates for sulfoxidation, as follows: phorate, CYP1A2, 3A4, 2B6, 2C9*1, 2C18, 2C19, 2D6*1, and FMO1; disulfoton, CYP1A2, 3A4, 2B6, 2C9*1, 2C9*2, 2C18, 2C19, 2D6*1, and FMO1; sulprofos, CYP1A1, 1A2, 3A4, 2C9*1, 2C9*2, 2C9*3, 2C18, 2C19, 2D6*1, and FMO1; methiocarb, CYP1A1, 1A2, 3A4, 2B6, 2C9*1, 2C19, 2D6*1, and FMO1. Among these isoforms, members of the CYP2C subfamily often had the highest affinities and clearance rates. Moreover, sulfaphenazole, a CYP2C9 competitive inhibitor, inhibited disulfoton sulfoxidation by CYP2C9 (IC50 0.84 microM) as well as in HLMs. Ticlopidine, a CYP2C19 mechanism-based inhibitor, inhibited disulfoton sulfoxidation by CYP2C19 (IC50 after coincubation, 43.5 microM; IC50 after preincubation, 4.3 microM) and also in HLMs. Our results indicate that current models of the substrate binding site of the CYP2C subfamily would not effectively predict thioether pesticide metabolism. Thus, the substrate specificity of CYP2Cs is more extensive than is currently believed, and some reevaluation of structure-activity relationships may be required.
Topics: Aryl Hydrocarbon Hydroxylases; Catalysis; Chromatography, High Pressure Liquid; Cytochrome P-450 CYP2C19; Cytochrome P-450 CYP2C9; Cytochrome P-450 Enzyme System; Enzyme Inhibitors; Humans; In Vitro Techniques; Isoenzymes; Microsomes, Liver; Mixed Function Oxygenases; Monoamine Oxidase; Spectrophotometry, Ultraviolet; Structure-Activity Relationship; Sulfaphenazole; Sulfides; Sulfoxides; Ticlopidine
PubMed: 14977868
DOI: 10.1124/dmd.32.3.333 -
Journal of Separation Science Jan 2012Analytical potentiality of a modified version of the QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method has been studied and validated for the extraction...
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.
Topics: Chromatography, Gas; Cicer; Flour; Food Contamination; Hordeum; Hot Temperature; Humans; Limit of Detection; Pesticide Residues; Pesticides; Solid Phase Extraction; Spectrometry, Mass, Electrospray Ionization
PubMed: 25940740
DOI: 10.1002/jssc.201100811