Determination of cyanocobalamin, betamethasone, and diclofenac sodium in pharmaceutical formulations, by high performance liquid chromatography.

The aim of this work was to develop an analytical method for a simultaneous determination of cyanocobalamin (Vitamin B12), betamethasone, and diclofenac, present in pharmaceutical formulations, by high performance liquid chromatography, assuring rapidity, accuracy, precision, and selectivity. The working conditions were as follows: RP18 column of 125 mm x 4 mm ID and a particle size of 5 microm; mobile phase acetonitrile-water (40:60; v/v) (pH* 3.45) adjusted with acetic acidl flow gradient from 0.8 to 1.9 ml/min.; injection volume of 20 microl; temperature 34 degrees C and detection at 240 nm. The method was adequately validated, and linearity, accuracy, as well as the system, method and interday precision, for each active principle, were determined.