Voltammetric studies on the electrochemical reduction of methylmercury in HCI aqueous medium at a carbon microelectrode

Fast scan voltammetry applied to methylmercury in chloride medium at a carbon fiber microelectrode has shown two cathodic peaks located at - 0.45 and -1.1 Vand a single anodic peak at - 0.33 V (vs. Ag | AgCl). It was concluded that the reoxidation process, at high sweep rates, in acidic media behaves as a reversible one-electron transfer process coupled to a chemical reaction, with the reaction product weakly adsorbed. Good linear calibration plots for the methylmercury determinations in the concentration range from 75 to 300 μM, have been obtained using the currents of the anodic peak measured on the CVs recorded, at 10 V s^-1, at a carbon fiber microelectrode, in a stationary solution of methylmercury chloride. Data have shown that the carbon microelectrode, cycled continuously in the analyte, can replace the dropping mercury electrode (DME), with the advantages that the carbon microelectrode is a promising tool for further studies in high resistive media, such as in natural waters.