High-performance liquid chromatographic determination of erythromycin

An isocratic, reversed-phase high-performance liquid chromatographic (HPLC) method has been developed for the determination of erythromycin. The method uses a muBondapak C18 reversed-phase column with a mobile phase composed of acetonitrile-methanol-0.2 M ammonium acetate-water (45:10:10:35). The relative standard deviation of the method for quantification of erythromycin is about 0.6%, and the method is capable of selectively quantifying erythromycins A, B, C and at least nine other erythromycin epimers and degradation compounds in 15 min of chromatographic time. The bio-equivalent potencies of erythromycin powders calculated from the HPLC data agreed well with those of the microbiological assay method. The HPLC method developed is also applicable for the analysis of various derivatives of erythromycin.