LOW-LEVEL ELECTROCHEMICAL DETECTION OF GLUCOSE-OXIDASE AND A GLUCOSE-OXIDASE CONJUGATE

An amperometric sensor for glucose oxidase is described. Partial optim ization of the working electrode potential at 0.4 V vs. Ag/AgCl, 0.1 M KCl at a glucose concentration of 30 mM allows a low detection limit of 50 pM glucose oxidase within 25 min. The sensor exhibits a high deg ree of precision and reproducibility, and the same electrode may be re -used for many successive quantitative determinations. A mechanism for the sensor is proposed, in which hydrogen peroxide generated by gluco se oxidase in bulk solution is oxidized at the working electrode, gene rating a current response that can be related to the glucose oxidase c oncentration. Conjugation of glucose oxidase with a coumarin-based pes ticide analogue does not affect the amperometric response.