Electro-Catalytic Oxidation of Ascorbic Acid at a Cobalt-Salen Polymer Modified Electrode and Analytical Applications

ABSTRACT The preparation and electrochemical characteristics of electrodes modified by cobalt complexes of N, N' - bis(salicylidene)-ethane -1, 2- diamine (salen) are described. A cobalt-salen polymer film modified electrode has strong electro-catalytic effects for the oxidation of ascorbic acid. The anodic peak potential of ascorbic acid shifted negatively for 400 m V. The catalytic reaction rate constant determined by rotating disk experiments is 7.08×105 mol s−1 cm3. The catalytic mechanism and the effect of film thickness are discussed. A sensitive voltammetric response for ascorbic acid was obtained covering a linear range from 1.0×10−6 to 1.0×10−3 mol-L−1 The modified electrode showed good stability and reproducibility. The electrode was used to the determination of ascorbic acid in fruit juices and showed promising results compared with conventional methods. The electro-catalytic effect of several metal-salen complexes and a similar Schiff base derivative for ascorbic acid was compared.

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