title: Direct high-performance liquid chromatographic enantioseparation of secondary amino acids on Cinchona alkaloid-based chiral zwitterionic stationary phases. Unusual temperature behavior.
abstract: Two chiral stationary phases containing a quinine- or a quinidine-based zwitterionic ion-exchanger as chiral selector were applied for the enantioseparation of 27 unusual cyclic secondary α-amino acids. The effects of the nature and concentration of the bulk solvent, the acid and base additives, the structures of the analytes and temperature on the enantioresolution were investigated. To study the effects of temperature and to obtain thermodynamic parameters, experiments were carried out at constant mobile phase compositions in the temperature range -5 to 55 °C. The thermodynamic parameters indicated that in most cases the separations were enthalpy-driven, but some entropy-driven separations were also observed. The sequence of elution of the enantiomers was determined in most cases.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
authors.forename: István
authors.initials: I
authors.lastname: Ilisz
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary; Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary.
authors.forename: Zsanett
authors.initials: Z
authors.lastname: Gecse
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
authors.forename: Zoltán
authors.initials: Z
authors.lastname: Pataj
authors.affiliation: Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary.
authors.forename: Ferenc
authors.initials: F
authors.lastname: Fülöp
authors.affiliation: Institute of Biochemistry, Biological Research Center, Temesvári krt. 62, H-6725 Szeged, Hungary.
authors.forename: Géza
authors.initials: G
authors.lastname: Tóth
authors.affiliation: Department of Analytical Chemistry, University of Vienna, Währinger Strasse 83, 1090 Vienna, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Lindner
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary. Electronic address: apeter@chem.u-szeged.hu.
authors.forename: Antal
authors.initials: A
authors.lastname: Péter
mesh_terms: D000470:Alkaloids / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002929:Cinchona / Q000737:chemistry*; D007098:Imino Acids / Q000302:isolation & purification*; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D000470:Alkaloids; D007098:Imino Acids
keywords: Column liquid chromatography; Quinine- and quinidine-based chiral zwitterionic ion-exchanger selectors; Unusual secondary amino acids; Unusual temperature behavior