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 diclofen ac, present in pharmaceutical formulations, by high performance liquid chro matography, assuring rapidity, accuracy, precision, and selectivity. The wo rking conditions were as follows: RP18 column of 125 mm x 4 mm ID and a par ticle size of 5 mu m; mobile phase acetonitrile-water (40:60; v/v) (pH* 3.4 5) adjusted with acetic acid; flow gradient from 0.8 to 1.9 ml/min.; inject ion volume of 20 mu l; temperature 34 degrees C and detection at 240 nm. Th e method was adequately validated, and linearity, accuracy, as well as the system, method and interday precision, for each active principle, were dete rmined. (C) 1999 Elsevier Science B.V. All rights reserved.