Multicomponent spectrometric assay of cyanocobalamin and its photoproduct hydroxocobalamin in the presence of ascorbic acid in photolyzed solutions

The simultaneous determination of cyanocobalamin (CC), hydroxocobalamin (HC) and ascorbic acid (AA) in aqueous solution has been achieved by a multicomponent spectrometric method. CC undergoes photolysis in acidic and alkaline media to form HC and the reaction is enhanced in the presence of AA. The method has been used to evaluate the kinetics of photodegradation reactions of the vitamin. CC, HC and AA present in the photolyzed solutions have been determined by absorbance measurement at 550, 525 and 265 nm at pH 4.0. These wavelengths correspond to the absorption maxima of the three substances and thus provide high specificity and sensitivity to the method. The method has been validated with respect to various parameters relating to the analytical performance characteristics. The recovery of the method for the three compounds ranges from 97.1-103.0% with a RSD value of ±3%. The accuracy of the method is shown by the linearity of the kinetic plots in the concentration range studied. The method is simple, rapid and convenient for the proposed work.