Spectrophotometric determination of benazepril hydrochloride and hydrochlorothiazide in binary mixture using second derivative, second derivative of the ratio spectra and chemometric methods

Different spectrophotometric methods are presented for the simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in pharmaceutical tablets. The first method depends on second derivative (2D) ultraviolet spectrophotometry, with zero crossing and peak to base measurement. The second derivative amplitudes at 214.8 and 227.4 nm were selected for the assay of benazepril hydrochloride and hydrochlorothiazide, respectively. The second method depends on second derivative of the ratio spectra by measurement of the amplitudes at 241.2 and 273.2 nm for benazepril hydrochloride and hydrochlorothiazide, respectively. Chemometric methods, classical least squares and principal component regression, were applied to analyze the mixture. Both the chemometric methods were applied to the zero and first order spectra of the mixture. The proposed methods were successfully applied for the determination of the two drugs in laboratory prepared mixtures and in commercial tablets.