Spectrophotometric determination of vitamin C using the copper(II)-nioxime-ascorbic acid system following stabilization in a propylene glycol medium

Abstract A spectrophotometric method for the determination of Vitamin C is proposed. The procedure is based on formation and stabilization of the ternary complex Cu(II)-nioxime-ascorbic acid in 80% ( v v ) propylene glycol-water medium. The method has a high degree of tolerance for the determination of ascorbic acid in the presence of other active substances or excipients likely to be present along with vitamin C in pharmaceutical formulations. The suggested method has proved to be rapid and precise and has been successfully applied to different commercial pharmaceutical preparations of vitamin C. Precision, measured on the relative standard deviation, did not exceed 0.73%.