Voltammetric studies of an oracet blue modified glassy carbon electrode and its application for the simultaneous determination of dopamine, ascorbic acid and uric acid

A stable modified glassy carbon electrode with oracet blue (OB) has been fabricated and its electrochemical behavior was investigated by cyclic voltammetry. The properties of the electrodeposited films, during preparation under different conditions, and the stability of the deposited films were examined. The charge transfer coefficient, a, and the charge transfer rate constant, k(s), for electron transfer between OB and glassy carbon electrode were calculated as 0.56 and 45.98 +/- 0.78 s(-1), respectively. The modified electrode shows electrocatalytic activity toward dopamine (DA) oxidation in phosphate buffer solution (pH 8.0) with a diminution of the overpotential of about 220 mV and an increase in peak current. The kinetic parameters such as the electron transfer coefficient, a, the heterogeneous rate constant, k', and the standard heterogeneous rate constant, k(0), for the oxidation of DA at the OBMGCE surface were determined using various electrochemical methods. The OBMGCE was applied to the electrocatalytic oxidation of dopamine (DA), ascorbic acid (AA) and uric acid (UA), and resolved the overlapping of the anodic peaks DA, AA and UA into three well-defined voltammetric peaks in differential pulse voltammetry (DPV). This modified electrode was quite effective not only to detect DA, AA and UA, but also in simultaneous determination of these species in a mixture. Also, the modified electrode exhibits the stable and sensitive responses for individual solutions of DA, AA and UA. The calibration curves for DA, AA and UA were linear for a wide range of concentrations of each species. (c) 2006 Elsevier B.V. All rights reserved.