Separation of erythromycin and related substances by high-performance liquid chromatography on...

A comparative evaluation of three brands of poly(styrene-divinylbenzene) copolymers, Hamilton PRP-1 (10 micron), Rogel (8 micron) and TSK-Gel (10 micron), as column packing materials for high-performance liquid chromatographic separation of erythromycins is presented. Erythromycins A, B and C, anhydroerythromycin A, erythromycin A enol ether, N-demethylerythromycin A, anhydro N-demethylerythromycin A and N-demethylerythromycin A enol ether were chromatographed. The effects of column temperature, concentration of organic modifier in the mobile phase, concentration of phosphate buffer, the addition of quaternary ammonium salts and pH are described. The best separations were obtained on TSK-Gel with the mobile phase acetonitrile-methanol-0.2 M tetramethylammonium hydroxide pH 8.0-0.2 M phosphate buffer pH 8.0-water (30:15:25:5:25). PRP-1 and Rogel gave equally good separations but with higher retention volumes.