The Electrochemical Behavior of Iron(III) Incorporated in Zeolite Y-Modified Electrode and the Catalytic Oxidation of Ascorbic Acid

Abstract

A new method is developed for the catalytic oxidation of ascorbic acid (AA) at a graphite-zeolite-modified electrode doped with iron(III) (Fe3+Y/ZCME), in which iron(III) exchanged in zeolite Y can act as catalyst to oxidize AA. First, the electrochemical behavior of iron(III) incorporated in the zeolite Y-modified electrode was studied. The results illustrate that diffusion controls the ferric/ferrous redox process at the Fe3+Y/ZCME. The anodic current of this process increases with the supporting electrolyte concentration of non-size-excluded cation and was suppressed when using size-excluded cation. Second, the catalytic oxidation of AA was explored at Fe3+Y/ZCME. With constant potential amperometric measurements optimal conditions for AA determination were obtained. The working potential was 0.55 V (vs. SCE); the supporting electrolyte was 0.1 M KNO3Or 0.05 M Na2HPO4-KH2PO4buffer solution (pH 6.8). The response current exhibits a linear relationship with the concentration of AA over the range of 1.58×10–6–2.15×10–2 M. When samples of urine, and fruit were analyzed with Fe3+Y/ZCME, we obtained AA recovery of 98–102%, and a relative standard deviation lower than 3%. Meanwhile, interferences from other ions and organic substances were examined.