ELECTROCHEMICAL OXIDATION AND KINETICS OF THE DECAY OF UV-ABSORBING INTERMEDIATE OF URIC-ACID OXIDATION AT PYROLYTIC-GRAPHITE ELECTRODES

The electrochemical oxidation of uric acid has been studied in 0.50 M NaCl and phosphate buffers of ionic strength 0.05 to 0.5 M. The kinetics of the decay of W-absorbing intermediate generated during electrooxidation of uric acid (7,9-dihydro-1H-purine-2,6,8-(3H)-trione) has also been studied. On the basis of pseudo first order rate constants observed in different media, it has been concluded that the diimine species formed from the 2e, 2H(+) oxidation of uric acid is attacked by water to give diol, which then decomposes in a series of reactions to give allantoin as the major product at pH 7.2. The possibility of attack by phosphate on dimine has been ruled out.