SPECTROFLUOROMETRIC DETERMINATION OF SOME PHARMACEUTICALLY IMPORTANT THIOXANTHENE DERIVATIVES

A simple, rapid and highly sensitive fluorimetric method is proposed for the determination of four pharmaceutically important thioxanthene derivatives, namely chlorprothixene, methixene hydrochloride, clopenthixol hydrochloride and flupentixol hydrochloride. The method is based on measuring the fluorescence produced by reaction with orthophosphoric acid. The fluorescence is measured at 544-548 nm after excitation at 368 nm. The calibration graphs are linear over the concentration ranges 0.1-1.3, 0.05-0.5, 0.2-2.0 and 0.2-2.0-mu-g ml-1 for the four compounds respectively. The method was applied to the determination of the compounds either in pure form or in their dosage forms. The results obtained are in agreement with those given by an official method.