Determination of ascorbic acid in pharmaceuticals using direct ultraviolet spectrophotometry

Abstract

A simple, rapid and accurate direct ultraviolet spectrophotometric method has been developed for the determination of ascorbic acid in pharmaceuticals. The sample blank is produced by the copper(II)-catalysed oxidation of the acid at room temperature. The absorbance measurements were made at 267 nm and pH 6. The proposed method is selective and many of the ingredients commonly found in ascorbic acid tablets and multi-vitamin preparations do not interfere. The method was utilised to determine ascorbic acid in vitamin C tablets, multi-vitamin preparations, calcium tablets and two cold-relief tablets, and the results obtained were compared with those from a BP method.