Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7611395 | Journal of Chromatography A | 2015 | 12 Pages |
Abstract
Stereoselective supercritical fluid chromatographic separations of the enantiomers of a large set of Nα-Fmoc proteinogenic amino acids were carried out on the recently developed Cinchona alkaloid-based zwitterionic chiral stationary phases Chiralpak ZWIX(+)⢠and ZWIX(â)⢠with protic solvents as co-solvents. The effects of the mobile phase composition, the natures and concentrations of the acid or base additives, the co- and counter-ions and temperature on the separations were investigated. The retention time in most cases slightly increased, while the separation factor decreased with increasing temperature. The changes in standard enthalpy, Î(ÎH°), entropy, Î(ÎS°), and free energy, Î(ÎG°), were calculated from the linear van't Hoff plots derived from the ln α vs 1/T curves in the studied temperature range (20-60 °C). The values of the thermodynamic parameters depended on the natures of the selectors and the structures of the analytes. On both ZWIX(+)⢠and ZWIX(â)⢠columns, enthalpically-driven separations were observed. The elution sequence was determined in all cases and was observed to be opposite on ZWIX(+)⢠and ZWIX(â)⢠which acted for the presented applications as chiral anion exchanger.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Gyula Lajkó, István Ilisz, Gábor Tóth, Ferenc Fülöp, Wolfgang Lindner, Antal Péter,