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

Xanthine oxidase has been immobilized on the surface of a CuPtCl6/glassy ca rbon chemically modified electrode. The enzyme electrode displays a quick a nd sensitive response to xanthine and hypoxanthine. The observed steady-sta te current is due to the oxidation of hydrogen peroxide Liberated during th e enzyme reaction on the surface of the enzyme electrode. The effects of en zyme loading, pH, temperature, and applied potential have been discussed. T he enzyme electrode was characterized as an amperometric sensor for xanthin e (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 cou pled with the enzyme electrode as an electrochemical detector was used to a nalyse the mixtures of xanthine and hypoxanthine. (C) 2000 Elsevier Science B.V. All rights reserved.