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Abstract

Simple and sensitive extractive spectrophotometric methods for the determination of Ethambutol in pure form and in pharmaceutical formulations using triphenyl methane dyes have been developed. The developed methods involve formation of coloured chloroform extractable ion-pair complexes of the drug with triphenyl methane dyes viz., bromocresol green (BCG), bromocresol purple (BCP) and bromophenol blue (BPB) in acidic medium. The extracted complexes formed with BCG, BCP and BPB showed absorbance maxima at 420, 419 and 415 nm respectively. The stoichiometry of the ion-pair complex is found to be 1:1 in each case. Beer's law is obeyed in the concentration ranges 2.0-25, 3.0-30 and 4.0-40 μg/ml with BCG, BCP and BPB respectively. The effect of concentration of dye, pH, and interference of excipients have been studied for optimization. The limits of detection and quantification have been determined for all the three methods. These methods have been validated as per the guidelines of ICH. The results of analysis were validated statistically through recovery studies.