Spectrophotometric Determination of Chiorpromazine -HC1 by Ion - Pair Complex Formation with Acid Dyes

A simple, rapid, accurate and sensitive spectrophotometric method is proposed for the determination of chiorpromazine -HC1 in pure form and in pharmaceutical formulation. This method is based on the formation of ion association complexes of drug with either thymol blue or bromophenol blue in an acidic buffer at pH values 4.17 and 3.68, respectively. The ion-pair complexes formed exhibit absorption maxima at 410nm for both thymol blue and bromophenol blue. These complexes are quantitatively extracted with chloroform. The calibration graphs are linear and obeyed Beer s law in a concentration range of 50-250ug/ml and 10-120|ig/ml with molar absorpitivites of 1.0374x10 and 1.7613x10* l.mol cm for thymol blue and bromophenol blue, respectively. Statistical treatment of the experimental results indicated that the method is precise, accurate and the procedure was successfully applied to the determination of the bulk drug and its pharmaceutical formulations.