Separation of enantiomers by open capillary electrochromatography on polysiloxane-bonded permethyl-beta-cyclodextrin

The separation of enantiomers by open capillary electrochromatography (o-CE C) using Chirasil-Dex as chiral stationary phase (CSP) is reviewed. In Chir asil-Dex, pertncthylated beta -cyclodextrin is linked via a single octameth ylene spacer to polydimethylsiloxane. The CSP is coated and thermally immob ilized onto the internal sur face of a fused-silica. column (i.d. 50 mum) E mploying a single open-tubular column coated with Chirasil-Dex, a unified e nantioselective approach can be realized using the four common chromatograp hic techniques: o-GC, o-SFC, o-LC and o-CEC, The chiral stationary phase Ch irasil-Dex can be combined with a charged cyclodextrin derivative, which is : added into the mobile phase. In the resulting dual chiral recognition sys tem, enhancement of enantioselectivity (matchcd case) or compensation of en antioselectivity (mismatched case) are observed. The overall enantioselecti vity is dependent on the sense of enantioselectivity of the selectors chose n and their influence on the electrophoretic and elecboos-motic migration o f the enantiomers of a selectand. The feasibility to couple chiral o-CEC an d ESI/MS is demonstrated for trace analysis of enantiomeric drugs in body f luids. (C) 2001 Elsevier Science B.V. All lights reserved.