Spectrophotometric and HPTLC-densitometric determination of lisinopril andhydrochlorothiazide in binary mixtures

Different spectrophotometric and HPTLC-densitometric methods are presented for the simultaneous determination of lisinopril and hydrochlorothiazide in pharmaceutical tablets. The spectrophotometric methods include third deriv ative (D-3) ultraviolet spectrophotometry with zero crossing measurement at 117.4 and 233.4 nm, second derivative of the ratio spectra with measuremen t at 214.3 and 228.0 nm; both classical least squares and principal compone nt regression were applied to the UV absorption and first derivative spectr a of the mixture. The HPTLC method was based on separation of both drugs fo llowed by densitometric measurements of their spots at 210 and 275 nm for l isinopril and hydrochlorothiazide. respectively. The separation was carried out on Merck HPTLC aluminum plates of silica gel 60 F-254, using chlorofor m-ethylacetate-acetic acid (10:3:2 by vol.) as mobile phase. The linear and second order polynomial were used for the regression equation of lisinopri l and hydrochlorothiazide, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.