Sensitive and selective determination of diclofenac sodium in pharmaceutical preparations by solid phase ultraviolet absorptiometry Original Research Article

A simple, sensitive and very selective spectrophotometric method for the determination of diclofenac sodium (DS) in pharmaceutical preparations 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 μg ml−1 of DS and the detection limit (calculated from K=3 criterion) was 0.086 μg ml−1. The RSD (n=10) was 1.05% for the determination of 3.80 μg 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 and 5-fold paracetamol as well as excipients, did not interfere.