Evaluation of kinetic parameters and redox mechanism of quinoxaline at glassy carbon electrode

Abstract

The electrochemical behavior of a biologically important heterocyclic compound quinoxaline (QUI) was investigated by cyclic voltammetry (CV) in solutions of differing pH, using a glassy carbon electrode (GCE). The reduction of QUI occurs as a quasi-reversible reaction in acid medium, reaching reversibility in alkaline solutions. The kinetic parameters of the electrode process such as ?n?, diffusion coefficient (D) and heterogeneous rate constant (ks), were evaluated and discussed. Redox mechanism of QUI was proposed on the basis of experimental results. Reduction process involves a transfer of two electrons and two protons at the pyrazine ring of QUI forming a dihydro-derivative. In acid solutions, the product of QUI reduction undergoes irreversible oxidation in a one-electron process. The electrode processes was found to be diffusion controlled.