Sensor film for Vitamin C determination based on absorption properties of polyaniline

An analytical method based on the absorption changes of chemically polymerised polyaniline at 700nm is proposed for the determination of Vitamin C. Vitamin C produces a polyaniline film reduction, originating changes in its absorbance proportional to the Vitamin C concentration. The optimum reaction conditions and the analytical characteristics have been studied. The linear response of the method ranged from 0.10 to 1.0mgl(-1) for a 6min reaction time and from 1.0 to 8.0mgl(-1) for a 2min reaction time. Reproducibility, expressed as the coefficient of variation, was 0.8% (6min reaction time) and 2.3% (2min reaction time) (n = 10). The method has been applied to Vitamin C determination in pharmaceutical preparations and commercial fruit juices. The results were compared with those obtained by the 2,6-dichlorophenolindophenol titration method (the AOAC Official Method) and no systematic errors were observed.