Spectrophotometric Estimation of Drugs Using N-Bromo Succinamide and Indigo Caramine Couple

Simple, specific, accurate and precise UV–visible spectrophotometric methods have been developed for the estimation of five drugs viz., Dobutamine hydrochloride (DOB), Domperidone(DOM), Duloxetine hydrochloride(DUL), Phenylephrine(PHE) and Trimetazidine(TRM). These methods involve the addition of a known excess of NBS to the drugs in acid medium followed by estimation of residual NBS by reacting with a fixed amount of Indigo Caramine and measuring the absorbance at 520nm. Beer’s law is obeyed in the concentration range of 0.6-4.2, 0.4-2.8, 0.3-2.1, 0.8-5.6 and 0.4-2.8 µg mL-1 for DOB, DOM, DUL, PHE and TRM respectively. Different variables affecting the reaction were studied and optimized. The proposed methods were applied successfully to the determination of the examined drugs in pure and pharmaceutical dosage forms with good accuracy and precision. The proposed methods were found to be successful for the estimation of these drugs in bulk and their formulations. The results of analysis have been validated statistically for linearity, accuracy, precision, LOD and LOQ.