Extractive Spectrophotometric Methods for Determination of Esmolol Hydrochloride Using Acidic Triphenylmethane Dyes

Three simple and sensitive extractive spectrophotometric methods have been described for the assay of Esmolol hydrochloride either in pure form or in pharmaceutical formulations. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with bromothymol blue (BTB), bromophenol blue (BPB) and bromocresol green (BCG) in acidic medium. The extracted complexes showed absorbances maxima at 415,412 and 412nm with BTB, BPB and BCG respectively. Beer's law is obeyed in the concentration ranges 2.5- 25μg/ml for all three dyes. The effect of concentration of dye and pH have been studied and optimized. The limits of detection and quantification have been determined for three methods. All the three methods have been validated as per the guidelines of ICH. The methods have been applied to the determination of drug in commercial tablets and results of analysis were validated statistically through recovery studies.