Abstract: A conducting polyaniline (PAn) film modified glassy carbon (GC) electrode was prepared by electrochemical polymerization. The electrochemical behavior of ascorbic acid (AH_2) in aqueous solution at this PAn modified electrode was studied in detail. The experimental results show that PAn film modified electrode has good electrocatalytic activity on the oxidation of ascorbic acid in aqueous solution over a wide range of pH value, among which pH 4 is the optimum condition. The oxidation process of ascorbic acid at PAn film electrode can be regarded as an EC catalytic mechanism. The kinetic process of the catalytic reaction was investigated by rotating disk electrode (RDE) coated with PAn films. The rate constant of the catalytic reaction was evaluated. The catalytic peak currents are proportional to the concentrations of ascorbic acid in the range of 5×10~(-2)—1×10~(-6) mol·L~(-1). The PAn film electrodes give very stable responce for the oxidation of ascorbic acid. The present investigation shows the posibility of using PAn film modified electrode for the determination of ascorbic acid.

Key words: Polyaniline, Ascorbic acid, Electrocatalytic oxidation, Kinetics, Modified electrode