Spectrophotometric Simultaneous Determination of Valsartan and Amlodipine Besylate in Combined Capsule Dosage form by Ratio Derivative Method

A simple, economical, precise and accurate method for simultaneous determination of valsartan (VAL) and amlodipine besylate (AML) in combined capsule dosage form has been developed. The method is based on ratio spectra derivative spectrophotometry. The amplitudes 229.48 nm and 299.10 nm in the first derivative of the ratio spectra were selected to determine valsartan (VAL) and amlodipine besylate (AML) respectively in combined formulation. Beer's law is obeyed in the concentration range of 8-40 μg mL^-1 for VAL and 0.5-2.5 μg mL^-1 for AML for the methods. The % assay for commercial formulation was found to be 98.56% ± 0.27 for VAL and 98.91% ± 0.51 for AML by the proposed methods. The methods were validated with respect to linearity, precision and accuracy. Recovery by both the methods was found in the range of 98.89 - 99.60 % for VAL and 98.58 - 99.63 % for AML.