Spectrophotometric determination of trifluoperazine via oxidative coupling reaction with sulfanilic acid

Abstract<br /> A simple spectrophotometric method has been developed for the determination of trifluoperazine hydrochloride in pure and in dosage forms. The method is based on the oxidative coupling reaction with sulfanilic acid in the presence of sodium hypochlorite in acetic acid medium to give an red coloured product with absorption maximum at 510 nm. The product is stable for more than 6 h. Beer's law is obeyed over the concentration range of 0.2–7.0 µg ml-1 with molar absorptivity of 5.15×103 l.mol-1cm-1. Different experimental parameters affecting the development and stability of the formed coloured product were carefully studied and optimized and a proposal of the reaction pathway was presented. The proposed method was applied successfully to the determination of trifluoperazine hydrochloride in tablets and compared favorably with the official method. Common excipients used as additives in pharmaceutical preparations do not interfere in the proposed method.