Use of immobilized enzyme coupled with an electrochemical sensor for the detection of organophosphates and carbamates pesticides.

The feasibility of an acetylcholinesterase electrode to detect pesticides is shown. The enzyme electrode is produced by coupling an electrochemical sensor (a slightly modified pH glass electrode) and an enzymic layer. Carbaryl (I) and azinphosethyl (II) are used as examples; typical recordings of the electrode signal and calibration curves are presented. The measurements were taken directly with inhibitor in the presence of substrate (I) or after incubation of the enzymic film (II). The electrode behavior can be modulated by varying the amount of enzyme immobilized in the film and by varying the concentration of substrate used during measurement. For I, the detection level is about 1.0 ppm and I50 = 6 10(-6) M, with acetylcholine as substrate. For II, the detection level is 1 ppm and I50 is dependent on the time of incubation. This new type of pesticide sensor could be used in air and water pollution control and is intended to be complementary to existing analytical methods.