Spectrophotometric determination of L-ascorbic acid in pharmaceutical preparations, foods and urine by formation of a 2-oximinocyclohexanone thiosemicarbazone-iron(II) complex

Abstract

A simple method is proposed for the determination of L-ascorbic acid in pharmaceutical preparations, foods and urine. The procedure is based on the rapid reduction of the iron(III) ion in the presence of L-ascorbic acid. The iron(II) formed is measured by reaction with 2-oximinocyclohexanone thiosemicarbazone (2-OCHT). The method has been used to determine L-ascorbic acid above 0.33 µg ml^–1, and the detection limit is 0.10 µg ml^–1. The results of the determination of L-ascorbic acid obtained using this procedure were comparable to those given by the 2,6-dichlorophenolindophenol (DIP) method.