Simultaneous determination of benazepril hydrochloride and hydrochlorothiazide in tablets by second-order derivative spectrophotometry

A second-order derivative spectrophotometric method for the simultaneous de termination of benazepril hydrochloride and hydrochlorothiazide in pharmace utical dosage forms is described. The determination of benazepril hydrochlo ride in the presence of hydrochlorothiazide was achieved by measuring the s econd-order derivative signals at 253.6 and 282.6 nm, while the second-orde r derivative signal at 282.6 nm was measured for the determination of hydro chlorothiazide. The linear dynamic ranges were 14.80-33.80 mu g ml(-1) for benazepril hydrochloride and 18.50-42.20 mu g ml(-1) for hydrochlorothiazid e, the correlation coefficient for the calibration graphs were better than 0.9998, n = 5, the precision (%RSD) was better than 1.43% and the accuracy was satisfactory (E-r < 0.99%). The detection limits were found to be 2.46 and 1.57 mu g ml(-1) for benazepril hydrochloride and hydrochlorothiazide, respectively. The method was applied in the quality control of commercial t ablets and proved to be suitable for rapid and reliable quality control. (C ) 1999 Elsevier Science B.V. All rights reserved.