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.
N-propylpyridinium chloride silsesquioxane polymer-coated graphite electrode; hexacyanoferrate(II) ion; electroacatalytic oxidation; amperometric determination; ascorbic acid
