Capillary electrochromatographic enantioseparations using a packed capillary with a 3 microm OD-type chiral packing

Enantiomer separations by capillary electrochromatography (CEC) using a packed capillary were investigated. As a chiral stationary phase, an OD-type packing material of 3 microm particle diameter, which is a silica-gel based material coated with cellulose tris(3,5-dimethylphenylcarbamate), was employed. The chiral packing was packed into a 100 microm I.D. fused-silica capillary by a pressurized method. Several racemic enantiomers were successfully resolved with acidic or basic buffers containing acetonitrile as mobile phases. The separation efficiencies obtained in this chiral CEC system were superior to those in the previously reported chiral CEC system using 5 microm particles. The typical plate heights obtained for several enantiomers were 4.6-6.6 microm or reduced plate heights of 1.5-2.2. Good repeatabilities in the migration time, peak height, and corrected peak area were observed as well as for the plate number. As an application study of this CEC system, an optical purity test was carried out by using benzoin enantiomers. A 1% content of one enantiomer in the other enantiomer was successfully separated and detected.