- Oxidation of organophosphorus pesticides for the sensitive detection by a cholinesterase-based biosensor
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A potentiometric flow injection-type biosensor developed in our laboratory was used for the determination of organophosphorus pesticides (OPs). The principle of the biosensor is that the degree of inhibition of a sensor enzyme by an OP is dependent on the concentration of the pesticide. The sensor system consisted of a reactor with acetylcholinesterase (AChE) immobilized on a controlled pore glass and a detector with a tubular H+-selective membrane electrode. In order to examine the possibility of enhancing the sensitivity of the sensor by converting OPs to oxidized forms (stronger inhibitors), a comparison of the degree of enzyme inhibition by OPs at 10-6 M before and after their oxidation was made. All of the ten pesticides tested exhibited greater inhibitory power toward the sensor enzyme following oxidation. All of the oxidized pesticides at 10-6 M inhibited the sensor enzyme to a considerable degree, demonstrating the utility of the developed method for the class-specific determination of OPs. A calibration curve for diazinon, over the concentration range of 10-11-10-4 M, was obtained. The lower detection limit was 2 × 10-10 M. Treatment of the inhibited enzyme with pyridine-2-aldoxime restored the enzyme to near full activity, allowing repeated use of the sensor,
- Lee, Hye-Sung,Ah Kim, Young,Ae Cho, Young,Tae Lee, Yong
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p. 571 - 576
(2007/10/03)
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- DIMETHYLDIOXIRANE CONVERSION OF PHOSHINE SULFIDES AND PHOSPHOROTHIOATES INTO THEIR CORRESPONDING OXYGEN ANALOGUES
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Tributyl and triphenyl sulfides react with dimethyldioxirane to give the corresponding oxides in quantitative yields.The procedure has also been used for the rapid and clean conversion of several insecticidal phosphorothioates into their respective triester phosphates, which are compounds of interest as standards for toxicological and environmental studies.
- Sanchez-Baeza, Francisco,Durand, Gael,Barcelo, Damia,Messeguer, Angel
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p. 3359 - 3362
(2007/10/02)
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