| 11838436 |
Lee HS, Kim YA, Cho YA, Lee YT: Oxidation of organophosphorus pesticides for the sensitive detection by a cholinesterase-based biosensor. Chemosphere. 2002 Jan;46(4):571-6.
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 x 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. |
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