Electrochemical behavior of antioxidants: I. Mechanistic study on electrochemical oxidation of gallic acid in aqueous solutions at glassy-carbon electrode

Mechanism of electrochemical oxidation of gallic acid in aqueous phosphate buffer solutions of different pH's was studied at glassy-carbon electrode. The study was performed using cyclic, convolution-deconvolution sweep voltammetry, chronoamperometry and chronocoulometry. It gives two irreversible diffusion-controlled cyclic voltammetric waves at the entire range of pH. The electrochemical oxidation mechanism was proposed to be an ECEC-first order mechanism in which the two electron transfer steps and the two chemical follow-up deprotonation reactions are irreversible. The proposed mechanism was confirmed by digital simulation and the electrode kinetic parameters are estimated on comparing the simulated response with the experimental ones. (C) 2011 Elsevier B.V. All rights reserved.