Absorbance Subtraction Method for the Determination of Losartan Potassium and Hydrochlorothiazide in Bulk and Tablets

Abstract

A simple, accurate and precise method was proposed for the determination of losartan potassium and hydrochlorothiazide. The overlain spectra of losartan potassium and hydrochlorothiazide were found to have an isoabsorptive point at 266.9nm, while the spectrum of later is extended with an absorption maximum at 325 nm; where the former is not interfering, based on these spectral characteristics, simultaneous spectrophotometric determination of the two analytes in combined dosage was possible using absorbance subtraction method. The method showed good precision in term of repeatability and intermediate precision with relative standard deviations were less than 2% in both cases. The method’s accuracy was confirmed by the close agreement between the theoretical and actual concentrations of the analytes in nine laboratory prepared synthetic mixtures. The proposed method was successfully applied to the analysis of a commercial product, the assay results were 102.60% and 99.88%with %RSD 1.68 and 1.68for LSP and HCT, respectively.