Electrooxidation of Iohexol in Its Commercial Formulation Omnipaque on Boron Doped Diamond Electrode

This study investigated the electrochemical behavior of iohexol in its commercial formulation omnipaque on a boron-doped diamond electrode using cyclic voltammetry and chronoamperometry. The dependence of the anodic peak current density vs. iohexol concentration is linear and can be applied to the determination of the substrate concentration in environmental samples and pharmaceuticals. The iohexol electrooxidation on boron-doped diamond electrode is diffusion-controlled process and proceed via two ways: a direct electron transfers at the surface of boron-doped diamond electrode and an indirect oxidation mediated by in situ oxidative species. The iohexol electrooxidation in pH range from 2 to 6 includes exchange of 4 electrons and 1 proton, at pH superior to 6 it includes an exchanged of 2 electrons and 1 proton. The values of activation energy, anodic transfer coefficient, heterogenous rate constant, diffusion coefficient and the catalytic rate constant were 14.164 kJ mol-1, 0.428, 1.06 s-1, 4.47 cm2 s-1 and 3.61 M-1 s-1 respectively. It appears from those results that, on our electrode, for the high potential scan rates, few actives sites mainly those located at the electrode surface are involved in the iohexol oxidation process. As the potential scan rate decreases, more actives sites are involved in the process.