Derivative absorption spectrophotometry for the determination of atenolol in pharmaceutical drugs.

Atenolol is a medicinal drug administrated commonly for the treatment of arterial hypertension, angina pectoris and cardiac arrhythmias. Two methods were developed for determination of atenolol based on conventional and derivative UV absorption spectrophotometry. The calibration curves at 225 nm and 275 nm have linear ranges extended from (1-100) ppm and (1-500) ppm with relative standard deviations for the slopes of 0.68 and 0.99 and correlation coefficient of the 0.9999 and 0.9994 respectively. The effect of pH on the determination of atenolol at these two wavelengths was also investigated. The best pH for its determination was found to be 9. Frusemide and amiloride are antihypertensive drugs that are usually given concurrently with atenolol. They have a large effect on the determination of atenolol due to the overlapped spectra. Therefore derivative absorption spectrophotometry was developed for determination of atenolol in the presence of frusemide or amiloride in order to overcome this problem. First, second and fourth derivative spectra at 233 nm, 229 nm and 279 nm, respectively, were used for this purpose. The calibration curves for the first, second and fourth derivative spectra have a linear range of (0.1- 100) ppm, (0.5-200) ppm and (2-500) ppm with relative standard deviation of the slope of 0.32, 3.18 and 4.47 and correlation coefficient of 0.9998, 0.9994 and 0.9998, respectively. The effect of pH on the determination of atenolol using the derivative
methods was also investigated.