Indirect Spectrophotometric Estimation of Carvedilol via Oxidation and Bleaching of Eriochrome Black-T Color in Bulk Drug and Pharmaceutical Preparations

Abstract

Carvedilol (CAR) has been estimated by the indirect spectrophotometric method. The suggested method was based on the oxidation of CAR with an excess of potassium per-iodate (KIO 4 ) in the presence of hydrochloric acid, then the unreacted or the excess KIO 4 was bleaching the color of Eriochrome black-T dye (EBT), the absorbance of unreacted EBT has been estimated at wavelength 520 nm (the maximum absorption of EBT). The measured absorbance is directly proportional to the amount of CAR in the solution. All parameters affected of by the oxidation of CAR and bleaching of EBT color have been studied and the optimum conditions have been fixed. The linearity of the method is in the range (0.5 -15.0) μg.ml-1, the molar absorptivity value is equal to 343121 10 4 l.mol -1 .cm -1 , and the Sandell's index value for sensitivity is equal to