Extraction and spectrophotometric determination of diclofenac in pharmaceuticals

A new simple, rapid and sensitive spectrophotometric method has been developed for the determination of diclofenac sodium (Dicl) in pharmaceutical preparations. This method is based on the reaction of diclofenac sodium with an analytical reagent 1,3,3-trimethyl-5-thiocyanato-2-[3-(1',3',3'-trimethyl-3'H-indol-2'-ylidene)-propenyl]-indolium cloride (TIC) at pH 8.0-11.0 and the extraction of ion associate colored complex. Optimal conditions for the complex formation between Dicl and TIC were studied. This ion associate complex (1: 1) was detected and extracted with toluene and an absorption maximum at 566.2 nm against a blank reagent. The calibration graph was linear from 0.9-11.0 mu g/mL of diclofenac and the detection limit was 0.86 mu g/mL.