Comparison of High - Performance Liquid Chromatography and Absorbance Ratio Methods for the Determination of Hydrochlorothiazide and Lisinopril in Pharmaceutical Formulations

The aim of this research was to study and to standardize a high-performance liquid chromatography (HPLC) and absorbance ratio method for the determination of hydrochlorothiazide and lisinopril in commercially available pharmaceutical dosage forms. An HPLC method has been developed for the simultaneous determination of hydrochlorothiazide and lisinopril from formulations, using acetonitrile:water (20:80 v/v) (pH 3.8), as a mobile phase at flow rate of 1.0 mlmin −1 and LiChrosorb RP -C 18 column (5 μ, 20cmx4.6 mm), as a stationary phase. Detection was carried out using a UV detector at 213.0 nm. In the second method, an absorbance ratio method, the determination of hydrochlorothiazide and lisinopril was performed by using the absorbances read at 272.0 nm, 258.8 nm and 262.7 nm in the zero-order spectra of their mixture. The absorbance ratio was also developed as a comparison method. The proposed methods, which give thoroughly comparable data, are simple and rapid, and allow precise and accurate results.