Abstract
A stability-indicating RP-UPLC method was developed for the quantification of related impurities of amlodipine basylate (AB) and Benazepril hydrochloride (BH) in solid pharmaceutical dosages form. The chromatographic separation employs a C18 column using a gradient elution, being solvent-A (1.36 g of potassium dihydrogen phosphate dissolved in one liter of water, adjusted to pH 3.0 with orthophosphoric acid) and solvent-B (acetonitrile) delivered at a flow rate of 0.3 mL min-1. The analytes were detected and quantified at 217 nm and 240 nm using photo diode-array detector. The method was validated demonstrating to be accurate and precise within the corresponding linear range of all components. The stability of the method was investigated under different stress conditions including hydrolytic, oxidative, exposed to photolytic, humidity and thermal as recommended by ICH guidelines. Relevant degradation was found under hydrolytic and oxidative conditions. Robustness against small modification in mobile phase pH, column oven temperature, flow rate and percentage of the mobile phase composition was ascertained. Lower limit of quantification and detection was also determined. The peak purity indices (purity angle < purity threshold) obtained with the aid of PDA detector and satisfactory resolution between related impurities established the specificity of the determination.