Catalytic Oxidation of Sulfite by Ferrocenemonocarboxylic Acid at the Glassy Carbon Electrode. Application to the Catalytic Determination of Sulfite in Real Sample

Abstract

Electrocatalytic oxidation of sulfite with some ferrocene derivatives such as ferroceneacetic acid, ferrocenemonocarboxylic acid and ferrocenemethanol as mediator were studied by cyclic voltammetry in aqueous solution with various pH at glassy carbon electrode. Results showed that the sulfite coupled catalytically only to ferrocenecarboxylic acid exihibiting homogeneous second-order rate constant Ks, 1.5×103 M−1 s−1. The catalytic oxidation peak current was linearly dependent on the sulfite concentration and the linearity range obtained was 4×10−4–1×10−2 M. Detection limit has been determined 2.5×10−4 M. This catalytic oxidation of sulfite has been applied as a selective, simple and precise new method for determination of sulfite in a real sample.