Extractive spectrophotometric determination of chlorpromazine and trifluoperazine hydrochloride in pharmaceutical preparations

A simple, accurate, and rapid extraction spectrophotometric procedure has been developed for the determination of some phenothiazine drugs such as chlorpromazine hydrochloride (CPH) and trifluoperazine dihydrochloride (TFPH) in pure form and their pharmaceutical preparations. The procedures are based on the reaction between the examined drugs (CPH and TFPH) and Alizarin Red S (AR), Bromocresol Purple (BCP), Chlorophenol Red (CPR) and Cresol Red (CR) producing ion-pair complexes which can be measured at the optimum wavelengths. The optimizations of the reaction conditions were investigated. Beer’s law is obeyed in the concentration ranges 1.77–96 μg ml−1. The molar absorptivity and Sandell sensitivity are also calculated. The correlation coefficient for both drugs was ⩾0.9995 (n = 5) with a relative standard deviation (R.S.D.) ⩽0.38. The methods are successfully applied to determine CPH and TFPH in pharmaceutical formulations.