title: High-performance liquid chromatographic enantioseparation of alpha-substituted glycine analogs on a quinine-based anion-exchanger chiral stationary phase under variable temperature conditions.
abstract: The retention of enantiomers of chiral analytes, i.e. alpha-substituted glycine analogs, on a quinine-based anion-exchanger chiral stationary phase was studied in the temperature range of 5-70 degrees C and at different mobile phase compositions, using isocratic elution in the reversed-phase mode. By variation of both mobile phase composition and temperature, baseline separations could be achieved for these enantiomers. Separation could be optimized more quickly by adjusting the column temperature rather than the mobile phase composition. The dependence of the natural logarithms of retention and selectivity factors (lnk' and lnalpha) on the inverse of temperature, 1/T (van't Hoff plots) was used to determine thermodynamic data on the enantiomers. Calculated thermodynamic constants (Delta(DeltaH degrees ), Delta(DeltaS degrees ) and Delta(DeltaG degrees )) were applied to promote an understanding of the thermodynamic driving forces for retention in this chromatographic system. The elution sequence of the enantiomers in most cases was determined.
authors.affiliation: Department of Inorganic and Analytical Chemistry, University of Szeged, P.O. Box 440, H-6701 Szeged, Hungary.
authors.forename: Roland
authors.initials: R
authors.lastname: Török
authors.forename: Robert
authors.initials: R
authors.lastname: Berkecz
authors.forename: Antal
authors.initials: A
authors.lastname: Péter
mesh_terms: D000837:Anion Exchange Resins / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D002930:Cinchona Alkaloids / Q000737:chemistry; D005998:Glycine / Q000031:analogs & derivatives / Q000737:chemistry / Q000302:isolation & purification*; D015394:Molecular Structure; D011803:Quinine / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D013696:Temperature; D013816:Thermodynamics
chemical_list: D000837:Anion Exchange Resins; D002930:Cinchona Alkaloids; D011803:Quinine; D005998:Glycine