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Enantiomeric analysis of baclofen analogs by capillary zone electrophoresis, using highly sulfated cyclodextrins: Inclusion ionization constant p K a determination
Author(s) -
Vaccher MariePierre,
Lipka Emmanuelle,
Bonte JeanPaul,
Foulon Catherine,
Goossens JeanFrançois,
Vaccher Claude
Publication year - 2005
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.200410311
Subject(s) - capillary electrophoresis , chemistry , enantiomer , beta cyclodextrins , electrophoresis , chromatography , cyclodextrin , inclusion compound , stereochemistry
Abstract Using cyclodextrin‐capillary zone electrophoresis (CD‐CZE), baseline separation of baclofen phaclofen, saclofen, and hydroxy‐saclofen, potent γ‐aminobutyric acid B (GABA B ) agonist or antagonists was achieved. A method for the enantioresolution of those analogs of GABA was developed using anionic cyclodextrins (highly sulfated CD or highly S‐CD) as chiral selectors and capillaries dynamically coated with polyethylene oxide (PEO). With charged CDs we observed good resolutions due to the large electrophoretic mobility of these chiral selectors opposite to the mobility of the solutes. The highly S‐α‐CD and S‐β‐CD were found to be complementary and the most effective complexing agent, allowing good enantiomeric resolution in short runtimes. The complete resolution was obtained using 25 m M phosphate buffer at pH 2.5 containing 3% w/v of highly S‐α‐CD or S‐β‐CD at 25°C with an applied field of 0.30 kV/cm. The apparent binding constants of the inclusion complexes were evaluated and the migration order was determined. A comparison was possible to investigate the importance of the anionic group of the molecules in the separations. The p K a values were determined for all four compounds in order to explain relative electrophoretic migration of the solutes.