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.
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.
Ilisz
István
I
Department of Inorganic and Analytical Chemistry, University of Szeged, Dóm tér 7, H-6720 Szeged, Hungary.
Pataj
Zoltán
Z
Berkecz
Róbert
R
Misicka
Aleksandra
A
Tymecka
Dagmara
D
Fülöp
Ferenc
F
Choi
Hee Jung
HJ
Hyun
Myung Ho
MH
Péter
Antal
A
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
D000596:Amino Acids; D043844:Crown Ethers; C090732:18-crown-6 2,3,11,12-tetracarboxylic acid; D000432:Methanol