title: Infinite enantiomeric resolution of basic compounds using highly sulfated cyclodextrin as chiral selector in capillary electrophoresis.
abstract: Four chiral basic analytes, namely methadone, fluoxetine, venlafaxine, and tramadol, were selected as model compounds for investigating their stereoselective separation with highly sulfated gamma-cyclodextrin (HS gamma-CD) by capillary electrophoresis (CE)-UV and CE-mass spectrometry (MS). At high concentration of chiral selector, the preferentially bonded enantiomer migrated faster in the anodic mode to the detector and high resolutions were obtained for all analytes. In the cathodic mode, at lower highly sulphated cyclodextrin (HS-CD) concentration, basic compounds could be detected, with the weakly bonded enantiomer migrating first (enantiomeric migration order inversion). It was also then possible, at intermediate HS-CD concentration, that only one enantiomer migrated to the detector as cation while the other enantiomer complexed with the CD was negatively charged and presented an opposite mobility. The latter never reached the detector achieving a perfect enantiomeric selectivity. Infinite chiral resolutions were thus achieved by CE-UV as well as by CE-electrospray ionisation (ESI)-MS where concentrations of HS-CD were adapted according to the negative contribution of the nebulization gas pressure of the interface.
authors.affiliation: Laboratory of Pharmaceutical Analytical Chemistry, School of Pharmacy, University of Geneva, 20 Boulevard d'Yvoy, CH-1211 Geneva, Switzerland. serge.rudaz@pharm.unige.ch
authors.forename: Serge
authors.initials: S
authors.lastname: Rudaz
authors.forename: Enrica
authors.initials: E
authors.lastname: Calleri
authors.forename: Laurent
authors.initials: L
authors.lastname: Geiser
authors.forename: Samir
authors.initials: S
authors.lastname: Cherkaoui
authors.forename: Josiane
authors.initials: J
authors.lastname: Prat
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Veuthey
mesh_terms: D003505:Cyclodextrins / Q000737:chemistry*; D003511:Cyclohexanols / Q000302:isolation & purification; D019075:Electrophoresis, Capillary / Q000379:methods*; D005473:Fluoxetine / Q000302:isolation & purification; D013058:Mass Spectrometry; D008691:Methadone / Q000302:isolation & purification; D013237:Stereoisomerism; D014147:Tramadol / Q000302:isolation & purification; D000069470:Venlafaxine Hydrochloride
chemical_list: D003505:Cyclodextrins; D003511:Cyclohexanols; D005473:Fluoxetine; D014147:Tramadol; D000069470:Venlafaxine Hydrochloride; D008691:Methadone