Liquid chromatography of erythromycin A and related substances on poly(styrene-divinylbenzene)

Summary An isocratic liquid chromatography method for assay and purity control of erythromycin is presented. Erythromycin A is separated from all its potential impurities, except erythromycin D. The selectivity depends on the pore size of the poly(styrene-divinylbenzene) stationary phase. Wide pore PLRP-S 8 μm 1000 ? shows the best selectivity. The column is heated at 70°C. The mobile phase is acetonitrile-2-methyl-2-propanol-0.2 M potassium phosphate buffer pH 9.0-water (3:16.5:5:75.5). The flow rate is 2 ml/min. UV detection is performed at 215 nm. The total analysis time is about 30 min. The method was used to compare official standards.