Potentiometric Determination of Valsartan in a Pharmaceutical Preparation and Its Protonation Constants

Abstract

A potentiometric titration method for determination of valsartan in pharmaceutical dosage forms is developed and validated. From the titration data stochiometric protonation constants are also calculated and these constants are found to be 4.57 and 5.47. The investigations were carried out in ethanol solutions using NaOH as titrant, at constant tempe-rature of 25.0 ± 0.1 °C and ionic strength of 0.10 M NaCl. The method was found to be reliable and precise, having a relative standard deviation of less than 1.0 % for valsartan. Commercial tablets containing 160 mg valsartan were successfully analyzed by the developed method. The validity of the method was tested by the recovery studies of standard addition to a pharmaceutical preparation and the results were found to be highly satisfactory. The proposed method is simple, rapid and sufficiently precise for quality control purposes of pharmaceuticals.