PACKED-CAPILLARY ELECTROCHROMATOGRAPHIC SEPARATION OF THE ENANTIOMERS OF NEUTRAL AND ANIONIC COMPOUNDS USING BETA-CYCLODEXTRIN AS A CHIRAL SELECTOR - EFFECT OF OPERATING PARAMETERS AND COMPARISON WITH FREE-SOLUTION CAPILLARY ELECTROPHORESIS

Chiral separation by packed capillary electrochromatography was successfully achieved through the use of 50 mu m I.D. fused-silica capillaries packed with a beta-cyclodextrin chiral stationary phase. The properties of electroosmosis in these packed capillaries were studied by investigating the influence of buffer composition and pH on the velocity of electroosmotic flow. With the use of triethylammonium acetate (TEAA) as background electrolyte, the direction of electroosmotic flow was reversed compared to the direction of flow observed with a phosphate buffer system. The enantiomers of both neutral solutes (benzoin, hexobarbital) and anionic solutes (dansyl- and dinitrophenyl-amino acids) were resolved; the analysis of anions was facilitated by the reversal of electroosmotic flow with the TEAA buffer system. The effects of methanol concentration and the TEAA buffer concentration on the migration and resolution of the enantiomers were studied. In addition, separations were obtained using beta-cyclodextrin as an additive in free-solution capillary electrophoresis using both phosphate and TEAA buffers. Comparison between the packed- and open-tubular systems was made. The same effect of electroosmotic flow reversal with TEAA buffer was observed in open-tubular fused-silica capillaries.