Enantiomer separation by capillary electrochromatography on a cyclodextrin-modified monolith

• Published in: Electrophoresis Vol. 21; no. 15; pp. 3152 - 3159
• Main Authors: Wistuba, Dorothee, Schurig, Volker
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.09.2000
• Subjects: Barbiturates - chemistry; Barbiturates - isolation & purification; Carbohydrate Conformation; Carbohydrate Sequence; Chirasil-Dex; Cyclodextrins - chemistry; Electrochromatography; Electrophoresis, Capillary - instrumentation; Electrophoresis, Capillary - methods; Enantiomer separation; Hexobarbital - chemistry; Hexobarbital - isolation & purification; Molecular Sequence Data; Monolith; Permethyl-β-cyclodextrin; Siloxanes - chemistry; Stereoisomerism
• ISSN: 0173-0835; 1522-2683
• DOI: 10.1002/1522-2683(20000901)21:15<3152::AID-ELPS3152>3.0.CO;2-L

A chiral monolithic stationary phase was prepared by packing a capillary with bare porous silica and sintering the silica bed at high temperature. The resulting silica monolith was polymer‐coated with Chirasil‐Dex, a permethylated β‐cyclodextrin covalently linked via an octamethylene spacer to dimethylpolysiloxane. Subsequently, Chirasil‐Dex was thermally immobilized on the silica support and a chiral monolith of very high stability (30 kV, more than 400 bar pressure) was obtained. The enantiomer separation of various chiral compounds by monolithic (rod) capillary electrochromatography (rod‐CEC) was feasible. This method was compared with capillary liquid chromatography (LC) in a single‐column mode using unified equipment. About two to three times higher efficiency was found in the rod‐CEC mode as compared to rod‐LC. The influence of pressure‐driven flow support on efficiency, resolution, elution time and baseline stability was investigated. The amount and nature of organic modifier strongly influences efficiency and resolution.