Development of Indirect Spectrophotometric Method for Quantification of Cephalexin in Pure Form and Commercial Formulation Using Complexation Reaction

Abstract

A simple, accurate and indirect spectrophotometric method was developed for the quantification of cephalexin in pure form and pharmaceutical products using complexation reaction. The developed method is based on the oxidation of the cephalexin with Fe (III) in acidic medium. Then 1, 10-phenanthroline reacts with Fe (II) and a red colored complex was formed. The absorbance of the complex was measured at 510 nm by spectrophotometer. Different experimental parameters affecting the complexation reactions were studied and optimized. Beer’s law was obeyed in the concentration range 0.4 -10 µg mL^-1 with a good correlation of 0.992. The limit of detection and limit of quantification were found to be 0.065 µg mL^-1 and 0.218 µg mL^-1, respectively. The method have good reproducibility with a relative standard deviation of 6.26 % (n = 6). The method was successfully applied for the determination of cephalexin in bulk powder and commercial formulation. Percent recoveries were found to range from 95.47 to 103.87 % for the pure form and 98.62 to 103.35 % for commercial formulations.