SIMULTANEOUS ANALYSIS OF A TERNARY MIXTURE OF PHARMACEUTICALS CONTAINING TRIMETHOPRIM, SULFAMETHOXAZOLE, AND PHENAZOPYRIDINE HYDROCHLORIDE USING 3RD-DERIVATIVE AND ZERO-ORDER PHOTODIODE-ARRAY SPECTROPHOTOMETRY

A simple and rapid method for the simultaneous analysis of a ternary m ixture containing trimethoprim, sulphamethoxazole and phenazopyridine hydrochloride is reported. The procedure consists of extraction in 0.1 M hydrochloric acid, filteration and measurement of the amplitudes of the third-derivative spectra at 242 and 276 nm and the absorbance at 450 nm for the determination of trimethoprim, sulphamethoxazole and ph enazopyridine hydrochloride, respectively. Good linearity, accuracy, p recision and selectivity were found, and the method is proposed for ro utine quality control purposes, even for the uniformity of contents te st.