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Dual chiral recognition system involving cyclodextrin derivatives in capillary electrophoresis II. Enhancement of enantioselectivity
Author(s) -
Jakubetz Hansjörg,
Juza Markus,
Schurig Volker
Publication year - 1998
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.1150190523
Subject(s) - capillary electrophoresis , cyclodextrin , chemistry , dual (grammatical number) , combinatorial chemistry , chromatography , literature , art
Abstract The enantiomer separation of hexobarbital was investigated by open tubular electrochromatography (OTEC) using the chiral stationary phase (CSP) CHIRASIL‐DEX (a permethylated β‐cyclodextrin covalently linked to a dimethyl‐polysiloxane) and by cyclodextrin‐electrokinetic chromatogaphy (CD‐EKC) using anionic β‐cyclodextrin‐sulfo‐ n ‐propyl ether (SPE‐β‐CD) and cationic β‐cyclodextrin‐2‐hydroxy‐3‐trimethylammoniumpropyl ether chloride (HTAP‐β‐CD) added to the running buffer. By employing two chiral selectors, the enantiomer separation of hexobarbital was then studied simultaneously by OTEC with CHIRASIL‐DEX and by CD‐EKC with either SPE‐β‐CD or HTAP‐β‐CD in the dual chiral recognition mode. In conjunction with CHIRASIL‐DEX, anionic SPE‐β‐CD decreased the chiral separation factor α due to compensation of enantioselectivity whereas the cationic additive HTAP‐β‐CD increased the chiral separation factor α due to enhancement of enantioselectivity. It is concluded that CHIRASIL‐DEX imparts an opposite enantioselectivity to the enantiomers of hexobarbital as compared to the charged CDs SPE‐β‐CD and HTAP‐β‐CD. Unusual peak broadening phenomena are observed in the dual chiral recognition system comprised of CHIRASIL‐DEX and HTAP‐β‐CD. The possible consequences of accidental dual chiral recognition systems caused by wall stacking effects of the mobile phase additives onto the inner surface of the capillary column are discussed.