Enantiomeric Separations by Capillary Electrochromatography with Charged Polyacrylamide Gels Incorporating Chiral Selectors

Abstract

This study examined enantiomeric separation by capillary electrochromatography with charged polyacrylamide gels incorporating chiral selectors, in which electroosmotic flow would be generated. The columns are capillaries filled with a negatively or positively charged polyacrylamide gel, a so-called monolithic stationary phase, incorporating polymeric β-cyclodextrins as chiral selectors. The capillary wall is activated first with a bifunctional reagent to make the resulting gel bind covalently to the inner surface of the fused-silica tubing. Enantiomeric separations of two cationic and a neutral compounds were achieved using negatively charged polyacrylamide gel-filled capillaries incorporating poly β-cyclodextrin and carboxymethyl β-cyclodextrin polymer and a mobile phase of 200 mmol dm−3 Tris–300 mmol dm−3 boric acid buffer (pH 9.0). Enantiomeric separations of twelve anionic compounds were also achieved using positively charged polyacrylamide gel-filled capillaries incorporating poly β-cyclodextrin and a mobile phase of 200 mmol dm−3 Tris–300 mmol dm−3 boric acid buffer (pH 8.1). High efficiencies of up to 240000 plates m−1 were obtained. The within-run reproducibilities of retention time and separation factor were good.