SENSITIVE AND SELECTIVE DETERMINATION OF DICLOFENAC SODIUM IN PHARMACEUTICAL PREPARATIONS BY SOLID-PHASE ULTRAVIOLET ABSORPTIOMETRY

A simple, sensitive and very selective spectrophotometric method for t he determination of diclofenac sodium (DS) in pharmaceutical preparati ons is described based on the fixation of the DS on Sephadex QAE A-25 resin at pH 7.0 and direct measurement of the absorbance of the solid phase at 281 and 400 nm. The calibration graph was linear from 0.40- 5 .75 mu g ml(-1) of DS and the detection limit (calculated from K=3 cri terion) was 0.086 mu g ml(-1). The RSD (n=10) was 1.05% for the determ ination of 3.80 mu g ml(-1) of DS. The method was applied to authentic pharmaceutical preparations. Other active ingredients, e.g., 50-fold thiamine chlorhydrate, 40-fold methylcobalamine, 20-fold pyridoxine an d 5-fold paracetamol as well as excipients, did not interfere. (C) 199 8 Elsevier Science B.V. All rights reserved.