Electrochemical oxidation of xanthine at solid electrodes

Abstract

The electrochemical oxidation of xanthine at glassy carbon electrode (GeE) and pyrolytic graphite electrode (PGE) has been studied in the <em>p</em>H range of 1.8-10.7 and found to proceed in a 4e, 4H⁺ reaction via the formation of uric acid at both the electrodes. Cyclic voltammetric behaviour, spectral studies, observed first order rate constant and product identification clearly point out that xanthine initially oxidizes in a 2e, 2H⁺ reaction to give uric acid which on subsequent oxidation gives the final products. The first order decay of UV absorbing intermediate has been monitored and the products have been identified. A plausible mechanism is suggested on the basis of observed experimental behaviour.