N-propylpyridinium Chloride Silsesquioxane Polymer Film on Graphite: Electrochemical Study of a Hexacyanoferrate (II) Ion Immobilized Electrode for Oxidation of Ascorbic Acid

Abstract

A well polished graphite surface was coated with a thin film of N-propylpyridinium chloride silsesquioxane polymer. On to the strongly graphite-adhered polymer film the electroactive species [Fe(CN)6]4- was adsorbed by means of an ion exchange reaction. The resulting electrode (graph/ SiPy+)4[Fe(CN)6]4- (graph = graphite and SiPy+ represents the N-propilpyridinium silsesquioxane polymer) was chemically very stable and was used to electrocatalytically oxidize ascorbic acid in solution (pH between 4.5-6.5) in 0.1 mol dm-3 KCl. The electrode was used to determine vitamin C in tablets and in processed orange juices. The results were in accord with those obtained by using the standard 2,6-dichlorophenolindophenol titration method.