Acta Pharm. 61 (2011) 37-50


full paper

Original research paper


Simultaneous spectrophotometric determination of valsartan and hydrochlorothiazide by H-point standard addition method and partial least squares regression


Department of Pharmaceutical Analysis, SRM College of Pharmacy, SRM University, Kattankulathur-603 203, India

Accepted February 4, 2011


Simultaneous determination of valsartan and hydrochlorothiazide by the H-point standard additions method (HPSAM) and partial least squares (PLS) calibration is described. Absorbances at a pair of wavelengths, 216 and 228 nm, were monitored with the addition of standard solutions of valsartan. Results of applying HPSAM showed that valsartan and hydrochlorothiazide can be determined simultaneously at concentration ratios varying from 20:1 to 1:15 in a mixed sample. The proposed PLS method does not require chemical separation and spectral graphical procedures for quantitative resolution of mixtures containing the titled compounds. The calibration model was based on absorption spectra in the 200-350 nm range for 25 different mixtures of valsartan and hydrochlorothiazide. Calibration matrices contained 0.5-3 g mL-1 of both valsartan and hydrochlorothiazide. The standard error of prediction (SEP) for valsartan and hydrochlorothiazide was 0.020 and 0.038, respectively. Both proposed methods were successfully applied to the determination of valsartan and hydrochlorothiazide in several synthetic and real matrix samples.


Keywords: valsartan, hydrochlorothiazide, H-point standard addition method, partial least squares regression, multicomponent analysis