Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Dimethoate”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources
PubMed1980

Gas-liquid chromatographic determination of organophosphorus insecticide residues in fruits and vegetables.

A method intended for regulatory purposes is described for the determination of organophosphorus insecticide residues in fruits and vegetables. Eighteen organophosphorus insecticides, azinphos-ethyl, chlorpyrifos, diazinon, dichlorvos, dimethoate, ethion, ethoate-methyl, fenitrothion, fenthion, formothion, malathion, methidathion, mevinphos, parathion, phosalone, phosphamidon, thiometon, and trichlorphon, and 7 metabolites, fenitrooxon, fenthion sulfoxide, fenthion sulfone, malaoxon, desethylphosphamidon, thiometon sulfoxide, and thiometon sulfone, were extracted from different crops with acetone and partitioned into hexane or ethyl acetate, according to their polarities. The hexane extract was cleaned up by eluting from a Florisil column with acetone-hexane (4+96). The ethyl acetate extract needs no cleanup. The concentrated extracts were analyzed by gas-liquid chromatography using thermionic detectors. Recoveries conducted at fortification levels ranging from 0.1 to 2 mg/kg were in most cases above 80%. The limit of sensitivity is less than 0.1 mg/kg.

Chromatography, Gas↗
PubMedDate not supplied

Improved gas chromatographic analysis of organophosphorus pesticides with pulsed splitless injection.

Gas chromatographic (GC) analysis of 6 organophosphorus pesticides (methamidophos, acephate, omethoate, diazinon, dimethoate, and chlorpyrifos) was performed with cool on-column, splitless, and pulsed splitless injections and with nitrogen-phosphorus or mass-selective detection. The pulsed splitless technique uses a high column flow rate during injection to sweep the sample out of the inlet rapidly, reducing analyte loss due to adsorption or thermal decomposition. After injection, the column flow rate is automatically reduced to normal values for chromatographic analysis. Pesticide recoveries for splitless and pulsed splitless injections were determined by comparison of GC peak areas with those obtained with cool on-column injection. With conventional splitless injection at a column flow rate of 5 mL/min, recoveries of acephate, omethoate, and methamidophos were only 57, 63, and 71%, respectively. Pulsed splitless methods with very fast injection flow rates dramatically improved recoveries, with all 6 pesticides falling in the 97-102% range. Because column flow rates are much less for GC with mass spectral detection (GC/MS), recoveries with splitless injection were lower and improvements with pulsed splitless injection were less dramatic for GC/MS. When splitless injection was used, recoveries of the 6 pesticides spiked into a green bean matrix were better than those of pesticides dissolved in pure solvent, presumably because matrix compounds compete with pesticides for active sites in the inlet. By using pulsed splitless injection of solvent standards with very fast initial column flow rates, systematic analyte losses in the inlet were eliminated, making recoveries of pesticides from solvent and green bean matrix very similar.

Chromatography, Gas↗
PubMed1996

[Evaluation of micronuclei in primary hepatocyte culture in rats treated with organophosphoric compounds].

We have evaluated the genotoxic effect of the three organophosphorous (OPs) insecticides dimethoate (DIM), azinphosmethyl (AZN) and diazinon (DIA) or in combination, at a ratio frequently found in foodstuffs by residual analysis. We have carried out the micronucleus (MN) test on cultured rat hepatocytes which were induced to proliferate by epidermal growth factor (EGF), and treated with the insecticides for 48 hours. The doses tested were chosen on the basis of cytotoxicity tests such as Trypan Blue exclusion and mitotic index inhibition. The results showed that AZN was the most toxic and DIM the least toxic compound. None of the compounds tested showed a genotoxic effect when examined separately. Conversely, a significant increase in MN frequency was observed when the three OPs were used in combination at the lowest concentration used when each compound was tested alone.

Animals↗
PubMedDate not supplied

Biosensors in flow-injection systems for biomedical analysis, process and environmental monitoring.

This paper presents the construction of various biosensors using thin-film layers incorporated in flow injection devices, providing automated systems for biomedical analysis, process and environmental monitoring. A urease sensor has been developed in conjunction with a flow injection system for the automatic determination of urea. Use of the spraying immobilization technique gives rise to a response time of a few seconds, which allows sample throughputs up to 200 h-1. With a penicillin biosensor adapted in an appropriate cell detection, on-line measurements of penicillin V in the fermentation broth are achieved during the whole fermentation process; the results are compared with the HPLC method. Linearity, sensitivity and reproducibility of the biosensor are studied with regards to sample dilution in a stirred flow detection cell to provide optimal operating conditions. Measurements without any change in parameters are obtained during the whole fermentation process. Acetylcholinesterase sensors have been used in batch systems for the determination of pesticides, but they require large amounts of substrate. When those enzyme sensors are combined with flow injection systems, only small volumes (100 microliters) of substrate are injected into the carrier stream and an automated system can be obtained for continuous control of water quality.

Biosensing Techniques↗
PubMed2004

Biochemical evidence that an S431F mutation in acetylcholinesterase-1 of Aphis gossypii mediates resistance to pirimicarb and omethoate.

Molecular changes in acetylcholinesterase (AChE) leading to target-site resistance to carbamate and organophosphate insecticides have recently been identified. Of particular interest is the S431F mutation in ace2 and its orthologue ace1 of Myzus persicae Sulzer and Aphis gossypii Glover, respectively. This mutation has been correlated with resistance to pirimicarb, but biochemical evidence has not yet been provided. Here, we describe for the first time that recombinantly expressed AChE1 from A gossypii carrying the S431F mutation is insensitive to pirimicarb and omethoate, but sensitive to demeton-S-methyl and hypersensitive to carbofuran. Furthermore, site-directed mutagenesis of the serine residue at position 431 in ace1 from a pirimicarb-susceptible clone of A gossypii conferred insensitivity to pirimicarb. We conclude that AChE1 of A gossypii is the target of toxicological relevance of carbamates and organophosphates.

Acetylcholinesterase↗
PubMed1999

Effect of acute exposure of the organophosphate insecticide Rogor on some biochemical aspects of Clarias batrachus (Linnaeus).

Indian catfish (Clarias batrachus), a common fish of commercial importance, was exposed to a sublethal concentration (1/3 of 96 h LC50 value) of Rogor for periods ranging from 24 to 192 h. The changes in glycogen, lactate, lactate dehydrogenase, and glycogen phosphorylase (a, ab) contents of muscle tissue were studied. A gradual decrease in muscle glycogen and an increase in lactate contents were observed. The activity level of lactate dehydrogenase showed a sharp rise initially for 48 h followed by a decline after 96 and 192 h. The glycogen phosphorylase a and ab in muscle tissue enhanced in response to Rogor exposure.

Animals↗
PubMed1981

Enzyme studies with human and hen autopsy tissue suggest omethoate does not cause delayed neuropathy in man.

Levels of acetylcholinesterase and neurotoxic esterase were measured in brain autopsy material. In tissue from a fatal human poisoning and from hens given 4-8 x unprotected LD50 AChE was highly inhibited and neurotoxic esterase uninhibited. The findings correlate with the inhibitory power of omethoate against these enzymes in vitro. It is concluded that omethoate has negligible potential to cause delayed neuropathy and a published report of human neuropathy due to omethoate is criticised.

Acetylcholinesterase↗