EXTRACTION-SPECTROPHOTOMETRIC DETERMINATION OF BENZOCAINE BY DICYCLOHEXYL-18-CROWN-6 AND CALMAGITE

Abstract

A simple and sensitive extraction-spectrophotometric method for rapid and accurate determination of benzocaine in pure and dosage forms was developed. Benzocaine was effectively extracted as a 1:1 ion pair complex with dicyclohexyl-18-crown-6 and calmagite in acidic media into chloroform, followed by spectrophotometric determination at 486 nm. Molar absorptivity of the ternary complex at this wavelength was 5.25×103 l mol-1 cm-1. Beer’s law was obeyed over the range 1.65-132 µg/ml of benzocaine and the minimum detectable amount of the drug was 0.6 µg/ml. The method was successfully applied to the determination of benzocaine in a cream sample.