Preparation of monodisperse porous polymethacrylate microspheres and their application in the capillary electrochromatography of macrolide antibiotics

Monodisperse poly(glycidyl methacrylate–divinylbenzene) microspheres were prepared by a simple one-step dispersion polymerization process. Examination of the polymeric microspheres showed that they had a mean particle diameter of 3 μm and dual pore size distribution with mean pore diameters of 300 and 800 Å. The microspheres were functionalized by introducing quaternary ammonium/octadecyl groups to obtain positively charged beads in a wide pH range. The functionalized beads were packed into fused-silica capillary having 50 μm inner diameter and used to separate erythromycin derivatives by capillary electrochromatography (CEC). These samples require gradient elution when separated by high-performance liquid chromatography (HPLC) or micro-HPLC, but with the new columns isocratic elution suffices for their separation by CEC. The column efficiency ranged from 40 000 to 50 000 theoretical plates.