Abstract
A simple, economic and validated spectrofluorimetric method was developed to assay cefixime (CFX). The technique relies on the quenching effect of CFX on the fluorescence intensity of eosin Y in the presence of acetate buffer pH 3.4 to produce an ion‐pair complex that is measured at 549 nm using an excitation wavelength of 300 nm. Reaction‐influencing factors were carefully investigated and optimized. The fluorescence quenching value was linear to the CFX concentration in the range 0.2–40 μg/ml with a correlation coefficient of 0.992. The calculated limit of detection and limit of quantification were found to be 0.00242 and 0.0080 μg ml−1, respectively. The selectivity of the method was confirmed by studying the effects of excipients and no interference was distinguished. The developed method was used to determine CFX in marketable products and in biological samples. To validate the method, directives of the International Conference on Harmonization were applied and per cent recoveries obtained ranged from 95.30 to 102.50% for pharmaceutical products and from 97.00 to 103.00% for biological fluids.
An ion‐pair complex was formed from electrostatic attraction through the reaction between the acidic carboxylate group of eosin Y and the amino group of cefixime and took place at acidic pH.