Capillary electrochromatographic separation of racemates on a norvancomycin-bonded monolithic column under reversed-phase conditions

Following a modified sol–gel process, a silica backbone was prepared in a fused-silica capillary, and it was then chemically modified with a glycopeptide antibiotic, norvancomycin (NVC), by a one-step in situ derivatization process. Several selected neutral and basic racemates were assessed on this column under reversed-phase conditions. The influences of pH and composition of mobile phase on enantioselectivity factor (α) and resolution (Rs) were also evaluated. A comparison was made between the NVC-bonded column with other similar capillary columns in published papers to demonstrate its better enantioselectivity. Furthermore, warfarin was chosen as model compound to study the self-preconcentration effect of racemates on this column. The preconcentration is marked in terms of peak heights, with up to 8–10-fold increase for the enantiomers of warfarin without obvious loss in column performance. Experimental data also show that the extent of preconcentration follows the retention factor (k) for a given enantiomer.