New insight into the EC’ mechanism of uric acid regeneration in the presence of ascorbic acid on a poly(3,4-ethylenedioxithiophene) modified gold electrode

Abstract

A gold electrode surface was functionalized by means of an electropolymerized conductive poly(3,4-ethylenedioxythiophene) (PEDOT) organic layer. This modified electrode was used for the electrochemical detection of ascorbic (AA) and uric (UA) acids in an aqueous mixture with a selectivity around 340 mV. The electrochemical reactions kinetics were limited by AA diffusion and UA adsorption at the electrode surface, respectively. Following a previous study ([Electrochem Comm., 2011, 13, 423-425]) cyclic voltammetry was used to provide a better understanding of the EC' mechanism of regeneration of UA by AA. Experiments particularly showed that allantoin (i.e. the final product of UA oxidation) is not actually involved in the synergic mechanism but rather the oxidized UA product diimine which is adsorbed at the electrode surface.