Xanthine and hypoxanthine sensors based on xanthine oxidase immobilized on a CuPtCl6 chemically modified electrode and liquid chromatography electrochemical detection

Xanthine oxidase has been immobilized on the surface of a CuPtCl6/glassy carbon chemically modified electrode. The enzyme electrode displays a quick and sensitive response to xanthine and hypoxanthine. The observed steady-state current is due to the oxidation of hydrogen peroxide Liberated during the enzyme reaction on the surface of the enzyme electrode. The effects of enzyme loading, pH, temperature, and applied potential have been discussed. The enzyme electrode was characterized as an amperometric sensor for xanthine (6 x 10(-7)-2 x 10(-4) M) and hypoxanthine (5 x 10(-7)-2 x 10(-4) M) with the detection limit of 1 x 10(-7) M. Liquid chromatographic separation coupled with the enzyme electrode as an electrochemical detector was used to analyse the mixtures of xanthine and hypoxanthine. (C) 2000 Elsevier Science B.V. All rights reserved.