Determination of carbamate pesticides by a cholinesterase-based flow injection biosensor

A potentiometric flow injection-type biosensor developed in our laboratory was used for the determination of carbamate pesticides. The principle of th e biosensor is based on the inhibition of enzyme by pesticides, which is de pendent on the concentration of the pesticides present. The sensor system c onsisted of a reactor with acetylcholinesterase immobilized on controlled p ore glass and a detector with tubular H+-selective membrane electrode. The sensor protocol established was applied to the analysis of nine carbamate p esticides. All the pesticides at 10(-6) M inhibited the sensor enzyme, demo nstrating the utility of the developed method. Treatment of the inhibited e nzyme with pyridine-2-aldoxime restored nearly all of the enzyme activity a llowing repeated use of the sensor. Calibration curves for carbaryl and car bofuran over the concentration range 10(-11)-10(-4) M were obtained. The lo wer detection limits were 10(-10) M and 10(-11) M, respectively.