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Journal of AOAC International 2003The separation of enantiomers and diastereomers of 8 commonly used pesticides was investigated by liquid chromatography (LC) using a Chiralcel OD column (cellulose...
The separation of enantiomers and diastereomers of 8 commonly used pesticides was investigated by liquid chromatography (LC) using a Chiralcel OD column (cellulose tris-3,5-dimethylphenylcarbamate as the chiral stationary phase) and a Pirkle-type Chirex 3020 column (urea derivative from the reaction of (R)-1-(alpha-naphthyl)ethylamine with (S)-tert-leucine, chemically bonded to 3-aminopropylsilanized silica as the chiral stationary phase). The pesticides studied included one organophosphorus insecticide (phenthoate), 3 triazole fungicides (uniconazole, diniconazole, and propiconazole), and 4 pyrethroids (fenpropathrin, beta-cypermethrin, beta-cyfluthrin, and alpha-fenvalerate). The enantiomers were separated within 20 min with a resolution of > or = 1.5 using a mixture of n-hexane and 2-propanol as the mobile phase for all the pesticides studied except propiconazole, for which only the 2 diastereomers were baseline separated. This method allows determination of the enantiomers or stereoisomers of the above pesticides in soil. The strategy was as follows: (1) First, the total concentration(s) of the enantiomer pair(s) of a chiral pesticide in soil was (were) determined by a newly developed matrix solid-phase dispersion (MSPD) procedure, followed by silica-based LC quantification. The recoveries ranged from 76.5 to 93.6% with relative standard deviations of 6.0%. (2) Second, the enantiomeric ratio(s) (ER(s)) of the chiral pesticide was (were) determined by LC with a chiral stationary phase after fractionation of the MSPD extract by silica-based LC. The determined ERs or stereoisomeric ratio(s) (SR(s); for propiconazole, only the SR of the 2 diastereomers was determined) in soil samples spiked with the above 8 racemic pesticides agreed with those of the corresponding standard solutions. (3) Third, based on the total concentrations and the corresponding ERs, the concentration of each enantiomer in soil was calculated. The proposed method is rapid, precise, and sensitive, and is appropriate for the investigation of the stereo- and enantioselective degradation of pesticides in environmental media.
Topics: Chromatography, Liquid; Pesticides; Soil; Stereoisomerism
PubMed: 12852570
DOI: No ID Found -
Journal of Chromatography. A Apr 2005In the present work, a novel sample pre-treatment technique for the determination of trace concentrations of some insecticide compounds in aqueous samples has been...
In the present work, a novel sample pre-treatment technique for the determination of trace concentrations of some insecticide compounds in aqueous samples has been developed and applied to the determination of the selected analytes in environmental water samples. The extraction procedure is based on coupling polypropylene hollow fiber liquid phase microextraction (HF-LPME) with gas chromatography by flame thermionic detection (GC-FTD). For the development of the method, seven organophosphorous insecticides (dichlorvos, mevinphos-cis, ethoprophos, chlorpyrifos methyl, phenthoate, methidathion and carbofenothion) and one carbamate (carbofuran) were considered as target analytes. Several factors that influence the efficiency of HF-LPME were investigated and optimized including agitation, organic solvent, sample volume, exposure time, salt additives and pH. The optimized methodology exhibited good linearity with correlation coefficient = 0.990. The analytical precision for the target analytes ranged from 4.3 to 11.1 for within-day variation and 4.6 to 12.0% for between-day variation. The detection limits for all analytes were found in the range from 0.001 to 0.072 microg/L, well below the limits established by the EC Drinking Water Directive (EEC 80/778). Relative recoveries obtained by the proposed method from drinking and river water samples ranged from 80 to 104% with coefficient of variations ranging from 4.5 to 10.7%. The present methodology is easy, rapid, sensitive and requires small sample volumes to screen environmental water samples for insecticide residues.
Topics: Chemical Fractionation; Hydrogen-Ion Concentration; Insecticides; Microchemistry; Reproducibility of Results; Water Pollutants, Chemical
PubMed: 15881459
DOI: 10.1016/j.chroma.2004.11.076 -
Journal of Chromatography. A Sep 2007A reliable multi-residue method which was based on solid-phase extraction (SPE) with multi-walled carbon nanotubes (MWCNTs) as adsorbent was developed for determination...
A reliable multi-residue method which was based on solid-phase extraction (SPE) with multi-walled carbon nanotubes (MWCNTs) as adsorbent was developed for determination and quantitation of 12 pesticides (carbofuran, iprobenfos, parathion-methyl, prometryn, fenitrothion, parathion-ethyl, isocarbofos, phenthoate, methidathion, endrin, ethion, methoxychlor) in surface water by gas chromatography-mass spectrometry (GC-MS). Parameters that might influence the extraction efficiency such as the eluent volume, the sample flow rate and the sample loading volume were optimized. The experimental results showed the excellent linearity of 12 pesticides (R(2)>0.99) over the range of 0.04-4 microg L(-1), and the precisions (RSD) were 3.1-15.1% under the optimal conditions. The detection limits of proposed method could reach 0.01-0.03 microg L(-1) based on the ratio of chromatographic signal to base line noise (S/N=3). Good recoveries achieved with spiked water samples were in the range of 82.0-103.7%. The results indicated that MWCNTs have good adsorbability to the 12 pesticides tested in this study. With less cost, less analytical time and less solvent-consuming, the developed multi-residue method could be used to determine multi-class pesticides in water simultaneously.
Topics: Gas Chromatography-Mass Spectrometry; Nanotubes, Carbon; Pesticide Residues; Sensitivity and Specificity; Solid Phase Extraction; Water; Water Pollutants, Chemical
PubMed: 17697685
DOI: 10.1016/j.chroma.2007.07.061 -
Journal of Toxicology and Environmental... 1985O,O,S-Trimethyl phosphorothioate (OOS-Me) is a pneumotoxic impurity present in various organophosphorus insecticides. OOS-Me produces morphological alteration of...
O,O,S-Trimethyl phosphorothioate (OOS-Me) is a pneumotoxic impurity present in various organophosphorus insecticides. OOS-Me produces morphological alteration of bronchiolar epithelial Clara cells accompanied by an increase in pulmonary lavage lactate dehydrogenase activity and severe weight loss in rats. Tolerance to the pneumotoxicity of OOS-Me was induced rapidly by oral pretreatments with small doses of OOS-Me itself. O,O-Dimethyl-S-ethyl phosphorothioate (OOS-Et), a pneumotoxic trialkyl phosphorothioate that is closely related in structure to OOS-Me, also produced a tolerance by oral pretreatment with small doses of OOS-Et itself. Pretreatment of rats with OOS-Me produced tolerance to OOS-Et, pretreatment did not produce tolerance to OOS-Me. Pretreatment of rats with tolerance-inducing doses of OOS-Me or OOS-Et had no effect on pulmonary or hepatic monooxygenase activities. Malathion and phenthoate carboxylesterases in pulmonary and hepatic microsomes were inhibited by these pretreatments. Activity of superoxide dismutase in lung or glutathione content in lung or liver was not affected by these pretreatments. Although the mechanism(s) remains unknown, the present study demonstrated the tolerance development to the chemical-induced pneumotoxicity.
Topics: Administration, Oral; Animals; Body Weight; Bronchi; Drug Tolerance; Glutathione; L-Lactate Dehydrogenase; Lung; Male; Microsomes, Liver; Organothiophosphates; Organothiophosphorus Compounds; Rats; Rats, Inbred Strains; Superoxide Dismutase
PubMed: 4009736
DOI: 10.1080/15287398509530654 -
Journal of the American Mosquito... Mar 1986A strain of Anopheles stephensi from Pakistan (MalR) was 8.7-fold resistant to malathion and 6.7-fold cross-resistant to phenthoate, but not to other carboxylesters; no...
A strain of Anopheles stephensi from Pakistan (MalR) was 8.7-fold resistant to malathion and 6.7-fold cross-resistant to phenthoate, but not to other carboxylesters; no cross-resistance to bendiocarb, fenitrothion, permethrin and carbaryl was detected. Resistance was not associated with elevated levels of general esterase activity, as determined by hydrolysis of naphth-l-yl acetate (alpha-NA), but was correlated with higher levels of malathion carboxylesterase (MCE) activity in vitro. The results suggest that a highly specific type of esterase mediated resistance, such as MCE, can best be detected by an enzyme specific assay rather than one for general esterase activity. A new, rapid and sensitive assay for mosquito MCE is given.
Topics: Animals; Anopheles; Carboxylic Ester Hydrolases; Hydrolysis; Insecticide Resistance; Insecticides; Larva; Malathion; Organothiophosphorus Compounds; Pakistan
PubMed: 3507466
DOI: No ID Found -
Journal of Chromatography. A Nov 1996A rapid procedure has been developed that allows a single-step, selective extraction and cleanup of organophosphate (OP) pesticide residues from milk dispersed on... (Comparative Study)
Comparative Study
A rapid procedure has been developed that allows a single-step, selective extraction and cleanup of organophosphate (OP) pesticide residues from milk dispersed on solid-matrix diatomaceous material filled into disposable cartridges by means of light petroleum saturated with acetonitrile and ethanol. Recovery experiments were carried out on homogenized commercial milk (3.6% fat content) spiked with ethanolic solutions of 24 OP pesticides, viz., ethoprophos, diazinon, dimethoate, chlorpyrifos-methyl, parathion-methyl, chlorpyrifos-ethyl, malathion, isofenphos, quinalphos, ethion, pyrazophos, azinphosethyl, heptenophos, omethoate, fonofos, pirimiphos-methyl, fenitrothion, parathion, chlorfenvinphos, phenthoate, methidathion, triazophos, phosalone, azinphos-methyl, at levels ranging for the different OP pesticides from 0.02 mg/kg to 1.11 mg/kg. Average recoveries of four replicates were in the range 72-109% for the different OP pesticides, with relative standard deviations (R.S.D.) from ca. 1 to 19%, while dimethoate and omethoate were not recovered. Coextracted fatty material amounted to an average of about 4.0 mg/ml of milk. The extraction procedure requires about 30 min. The main advantages are that extraction and cleanup are carried out in a single step, emulsions do not occur, several samples can be run in parallel by a single operator, reusable glassware is not needed and simple operations are required.
Topics: Animals; Chromatography, Gas; Insecticides; Milk; Organophosphorus Compounds; Pesticide Residues
PubMed: 8997741
DOI: 10.1016/s0021-9673(96)00535-3 -
Indian Journal of Experimental Biology Jun 1997Amines such as dopamine, norepinephrine and epinephrine were analysed in the brain regions of O.mossambicus exposed to quinalphos, phenthoate and their combination for... (Comparative Study)
Comparative Study
Amines such as dopamine, norepinephrine and epinephrine were analysed in the brain regions of O.mossambicus exposed to quinalphos, phenthoate and their combination for 96 hr. The three types of treatments significantly (P < 0.05) altered the amines level at various intervals in the brain regions.
Topics: Animals; Biogenic Amines; Brain; Organophosphorus Compounds; Stress, Physiological; Tilapia; Water Pollutants, Chemical
PubMed: 9357180
DOI: No ID Found -
Journal of Chromatography. A Oct 1998Application of supercritical fluid extraction (SFE) for selective isolation of organophosphorus pesticides from a real-world matrix (wheat flour) has been described. The... (Comparative Study)
Comparative Study
Application of supercritical fluid extraction (SFE) for selective isolation of organophosphorus pesticides from a real-world matrix (wheat flour) has been described. The method uses extraction with supercritical carbon dioxide at 206.8 bar and 60 degrees C, followed by quantitation by gas chromatography with nitrogen-phosphorous detection without clean-up of the extracts. Comparison of SFE with a method currently employed for sample preparation (i.e., organic solvent extraction followed by liquid-liquid extraction and gel permeation chromatography clean-up) shows that the SFE technique simplifies the sample preparation step and speeds up the determination of organophosphorus pesticides in flour. Extraction times were 60 min for a 7 g sample size. This technique was able to determine organophosphorus pesticides (ethoprophos, diazinon, chlorpyrifos methyl, fenitrothion, parathion, phenthoate, EPN) in samples at the 10 ng/g level.
Topics: Chlorpyrifos; Chromatography, Gas; Fenitrothion; Flour; Insecticides; Malathion; Parathion; Sensitivity and Specificity; Triticum
PubMed: 9818429
DOI: 10.1016/s0021-9673(98)00629-3 -
Sudebno-meditsinskaia Ekspertiza 1981
Topics: Cadaver; Humans; Methods; Organothiophosphorus Compounds
PubMed: 7314197
DOI: No ID Found -
Medicine, Science, and the Law Oct 1986
Topics: Chromatography, Gas; Humans; Male; Mass Spectrometry; Middle Aged; Organothiophosphorus Compounds
PubMed: 3784847
DOI: 10.1177/002580248602600403