Photodegradation of cyanocobalamin in the presence of ascorbic acid

ABSTRACT

The photodegradation of cyanocobalamin at pH 4.0 in the presence of ascorbic acid has been studied. Hydroxocobalamin has been identified as a major degradation product of the reaction. Cyanocobalamin and hydroxocoblamin in degraded solutions have been assayed at 550 and 525nm by a two-component spectrophotometirc method in which ascorbic acid does not interfere. The apparent first-order rate constants for the photodegradation of cyanocoblaamin at pH 4.0 are in the range of 2.21-2.70 x 10-3 min-1. These values indicate that the photodegradation of cyanocobalamin is enhanced in the presence of ascorbic acid by mutual interaction and needs protective measures to control the degradation of the vitamin