Chiral monolithic columns for enantioselective capillary electrochromatography prepared by copolymerization of a monomer with quinidine functionality. 1. Optimization of polymerization conditions, porous properties, and chemistry of the stationary phase

Monolithic columns for chiral capillary electrochromatography have been pre pared within the confines of untreated fused-silica capillaries in a single step by a simple copolymerization of mixtures of O-[2-(methacryloyloxy)eth yl-carbamoyl]-10,11-dihydroquinidine, ethylene dimethacrylate, and glycidyl methacrylate or 2-hydroxyethyl methacrylate in the presence of mixture of cyclohexanol and 1-dodecanol as a porogenic solvent. The porous properties of the monolithic columns can easily be controlled through changes in the c omposition of the binary porogenic solvent. Although both thermal- and UV l ight-initiated polymerizations afford useful capillary columns, monoliths p repared using the former approach exhibit better chromatographic properties . The ability to control pore size independently of the polymerization mixt ure composition enables the preparation of monoliths with varying percentag es of the chiral monomer and crosslinker, as well as the optimization of th eir separation properties. Very good separations of model racemate (R,S)-N- 3,5-dinitrobenzoylleucine were achieved using an optimized monolithic CEC c olumn, with high efficiencies of up to 74 000 plates/m for the retained pea ks.