Assay of Erythromycin from Human Serum by High Performance Liquid Chromatography with Electrochemical Detection

Abstract

A sensitive and selective method has been developed for the determination of serum concentrations of erythromycin A by high performance liquid chromatography with electrochemical detection. Erythromycin was extracted from alkalinized serum samples with methyl t-butyl ether. After evaporation of the ether, the samples were reconstituted in acetonitrile/ammonium acetate and washed with hexane. Aliquots were injected onto a Sepralyte diphenyl column. The mobile phase consists of acetonitrile/sodium perchlorate/ammonium acetate/methanol under isocratic conditions. Eluted peaks were detected by dual coulometric electrodes operated in the oxidative screen mode. The recovery of erythromycin from serum was 84%. Assay limit of quantification was 0.05 μg/ml serum, and dynamic linear range was 0.05–1.5 μg/ml. This method was used to quantitate both erythromycin and its gastric degradation products from human serum. Additionally, other macrolide antibiotics could be quantified by electrochemical detection. Analytical results for erythromycin compared favorably with those obtained with a standard microbiological assay.