Abstract

Simple, accurate and precise spectrophotornetric methods were developed for simultaneous estimation of atenolol and nifedipine in tablets and capsules using absorption correction method and first order derivative zero-crossing method. In the first method atenolol and nifedipine in methanol had λ max at 276.5 nm and 328.5 nm, showing linearity in the concentration range of 0-30 μg/ml and 0-25 μg/ml, respectively. The absorbance of the mixed standard solutions was measured at 328.5 nm and nifedipine was determined using E (1%, 1cm) value. The absorbances of the final dilutions was measured at 276.5 nm and the absorbance by atenolol was corrected at 276.5 nm. The content of atenolol was then calculated using E (1%, 1cm) value. In the second method the first derivative spectrum was determined. Atenolol showed zero crossing point at 226.5 nm while nifedipine showed zero crossing point at 235 nm. The dA/dλ was measured at 235 nm for atenolol and 226.5 nm for nifedipine and calibration curves were plotted as dA/dλ versus concentration respectively. Quantitative determination of atenolol and nifedipine in tablets and capsules was carried out using standard calibration curve of atenolol and nifedipine by interpolation method. Results of analysis for both the methods were validated statistically and by recovery studies.