INVESTIGADORES
KEUNCHKARIAN Sonia
artículos
Título:
Chiral ligand-exchange chromatography with Cinchona alkaloids. Exploring experimental conditions for enantioseparation of α-amino acids
Autor/es:
R. ECHEVARRÍA, C.A. FRANCA, M. TASCON, C.B. CASTELLS, S. KEUNCHKARIAN
Revista:
MICROCHEMICAL JOURNAL
Editorial:
ELSEVIER SCIENCE BV
Referencias:
Lugar: Amsterdam; Año: 2016 vol. 129 p. 104 - 110
ISSN:
0026-265X
Resumen:
The natural Cinchona alkaloid quinidine as chiral selector in chiral ligand-exchange chromatography was systematicallystudied. Chromatographic conditions for enantioseparation of twentyα-amino acidswere first timestudiedby changing mobile phase parameters such as pH, concentration of organic solvent, type of salt, ligand tometal ratio and also column temperature. Maximum retention and enantioselectivity factors were observed atthe region close to pH = 8, since the tertiary amine (the quinuclidinic nitrogen) of the quinidine is protonatedonly in a small degree, and therefore is available for the chelate formation. Additionally at this pH value thereis no other competing ligand for complex the metallic cation. The thermodynamic transfer parameters of theenantiomers from the mobile to the stationary phase from van´t Hoff plots within the range of 10?35 °C wereestimated. Thus, the differences in the transfer enthalpy Δ(ΔH), and transfer entropy Δ(ΔS) enabled an investigationof the origin of the differences in interaction energies Δ(ΔG). Finally, the molecular geometry of theformed diastereomeric complexes was modelled and energetic differences between both compounds were calculatedby a semi empirical method.
