title: High-performance liquid chromatographic enantioseparation of beta(2)-amino acids using a long-tethered (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid-based chiral stationary phase.
abstract: Reversed-phase high-performance liquid chromatographic methods were developed for the separation of enantiomers of eleven unnatural beta(2)-amino acids on a new chiral stationary phase, using the 11-methylene-unit spacer of aminoundecylsilica gel for the bonding of (+)-(18-crown-6)-2,3,11,12-tetracarboxylic acid as selector. The nature and concentration of the acidic and organic modifiers, the pH, the mobile phase composition, and the structures of the analytes substantially influenced the retention and resolution. Separations were carried out at constant mobile phase compositions in the temperature range 7-40 degrees C and the changes in enthalpy, Delta(DeltaH degrees ), entropy, Delta(DeltaS degrees ), and free energy, Delta(DeltaG degrees ) were calculated. The elution sequence was determined in some cases: the S enantiomers eluted before the R enantiomers.
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.forename: Zoltán
authors.initials: Z
authors.lastname: Pataj
authors.forename: Róbert
authors.initials: R
authors.lastname: Berkecz
authors.forename: Aleksandra
authors.initials: A
authors.lastname: Misicka
authors.forename: Dagmara
authors.initials: D
authors.lastname: Tymecka
authors.forename: Ferenc
authors.initials: F
authors.lastname: Fülöp
authors.forename: Hee Jung
authors.initials: HJ
authors.lastname: Choi
authors.forename: Myung Ho
authors.initials: MH
authors.lastname: Hyun
authors.forename: Antal
authors.initials: A
authors.lastname: Péter
mesh_terms: D000596:Amino Acids / Q000737:chemistry / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D043844:Crown Ethers / Q000737:chemistry*; D016014:Linear Models; D000432:Methanol / Q000737:chemistry; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D000596:Amino Acids; D043844:Crown Ethers; C090732:18-crown-6 2,3,11,12-tetracarboxylic acid; D000432:Methanol