A simplified colorimetric method for the determination of ascorbic acid in pure solutions and in pharmaceutical preparations

Abstract

A precise and specific method for the determination of L-ascorbic acid in the presence of dehydro-L-ascorbic acid and 2,3-diketo-L-gulonic acid has been developed. The method is based on the reaction of phenylhydrazinium chloride with ascorbic acid in 0·1 N hydrochloric acid at a temperature of 50 ± 2 °C. The stable yellow colour produced is measured spectrophotometrically at 395 nm. The results obtained by this method and the B.P. method are compared. There is no interference from other vitamins, minerals, glucose, sucrose or the most commonly used excipients with this method and it has been successfully applied to pharmaceutical preparations. The simplicity of the procedure permits rapid analysis, which is necessary for routine control work.