Author(s): Afaf Abou-elkheir*, Hanaa M. Saleh, Magda M. El-henawee, Basma El-sayedGhareeb
Four methods are developed for simultaneous determination of Atenolol and Chlorthalidone without previous separation. The first method depends on first derivative of the ratios spectra by measurements of the amplitudes at 235 nm for Atenolol and (236,249 nm) forChlorthalidone.The second method depends on measuring the absorbance at the isosbestic point at 283.5 nmfor the total concentration of both drugs while the concentration of Chlorthalidone is determined by direct spectrophotometric method at λmax 250 nm in the presence of Atenolol, the concentration of Atenolol is calculated by subtraction. The third method is factorized absorptivity method at which both drugs are determined at more than one isospestic point ( 265, 284.5 nm ).The fourth method involved application of the bivariate calibration algorithm for spectrophotometric simultaneous determination of the mixture. The suggested procedures are validated using laboratory prepared mixtures and are successfully applied for the analysis of pharmaceutical preparations. The methods retained their accuracy and precision when the standard addition technique is applied. The results obtained are statistically analyzed and compared with those obtained by the reference method.