Application of Bromophenol Blue and Bromocresol Purple for the Extractive-Spectrophotometric Determination of Ofloxacin

Abstract

Simple, rapid, and extractive spectrophotometric methods were developed for the determination of ofloxacin in bulk and pharmaceutical dosage form. These methods are based on the formation of yellow ion-pair complexes between the basic nitrogen of the drug and bromophenol blue and bromocresol purple as sulphonphthalein dyes in phthalate buffer pH 3.0 and pH 3.1, respectively. The formed complexes were extracted with chloroform and measured at 414 nm for ofloxacin–bromophenol blue and 408 nm for ofloxacin–bromocresol purple. The analytical parameters and their effects on the reported systems are investigated. The reactions were extremely rapid at room temperature and the absorbance values remains unchanged at 48 h for ofloxacin–bromophenol blue and 72 h for ofloxacin–bromocresol purple. Beer's law was obeyed in the ranges 0.87–17.35 and 0.58–14.46 µg mL−1 for ofloxacin–bromophenol blue and ofloxacin-bromocresol purple, respectively. The composition of the ion pairs was found 1:1 by Job's method. The proposed methods have been applied successfully for the analysis of the drug bulk form and its dosage form. The results obtained by the proposed methods were compared and statistical analysis showed no significant difference between the proposed methods.