Development and validation of a stability indicating analytical method for the related substances of Bosentan drug substance by HPLC

Abstract

An accurate & sensitive stability indicating analytical method has been developed for the control of impurities in Bosentan API. Four impurities (impurity A, B, C & D) were isolated from the API and were characterized by spectroscopic studies. An HPLC equipped with quaternary gradient pumps, variable wavelength UV detector attached with data recorder and integrator software was used. A Zorbax SB-C8 (250 x 4.6mm, 5µ) column at 25°C was used with a flow rate of 1.0 ml/min and the compounds were detected at 220 nm. Mobile phase A consisted of buffer (1gm of octane-1-sulfonic acid sodium salt and 1 ml triethyl amine in 1 liter of water, pH adjusted to 2.5 with perchloric acid) and methanol was used as mobile phase B. The method was validated according to the ICH guidelines with respect to specificity, linearity, range, accuracy, precision, limit of detection & quantification. Robustness testing was also conducted to evaluate the effect of minor changes to the chromatographic system and to establish appropriate system suitability parameters. All of them were found to be satisfactory for the method. Thus the method can very well be implemented in quality control laboratories and in stability testing departments.