The separation of enantiomers is of great importance in biology, pharmaceutics, agriculture and environment. The different separation modes (i.e. capillary zone electrophoresis (CZE), micellar electrokinetic chromatog...The separation of enantiomers is of great importance in biology, pharmaceutics, agriculture and environment. The different separation modes (i.e. capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), capillary electrochromatography (CEC), etc) and many chiral selectors available make capillary electrophoresis (CE) technique a powerful tool for chiral analysis[1]. On the basis of ligand-exchange (LE) mechanism introduced by Davankov and Rogozhin[2] in the early 1970s for high performance liquid chromatography (HPLC), the first application of CE in chiral separation was reported by Zare's group[3,4]. Using Cu(Ⅱ) complexes of L-histidine or aspartame as chiral selectors, 14 dansyl amino acids (Dns-AAs) were resolved. The authors observed a significant improvement in resolution when a micelle forming surfactant such as sodium dodecyl sulfate (SDS) was added to the electrolyte performing MEKC. The method was called as ligand-exchange micellar electrokinetic capillary chromatography (LE-MEKC). As a hybrid mode of possessing both the advantage of high enantioselectivity in ligand-exchange mechanism and the main advantages of MEKC, LE-MEKC allows the manipulation of the selectivity for large classes of neutral and charged compounds, making possible separation that otherwise are not feasible by using only the mode of LE or MEKC. Using this combined separation mode, hydroxy acids and dipeptides, as well as 16 positional and optical isomers of tryptophan derivatives could be optically resolved[5]. The same group also proposed a method for the determination of the critical micelle concentration (CMC) of anionic surfactants based on LE-MEKC principle[6].展开更多
文摘The separation of enantiomers is of great importance in biology, pharmaceutics, agriculture and environment. The different separation modes (i.e. capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), capillary electrochromatography (CEC), etc) and many chiral selectors available make capillary electrophoresis (CE) technique a powerful tool for chiral analysis[1]. On the basis of ligand-exchange (LE) mechanism introduced by Davankov and Rogozhin[2] in the early 1970s for high performance liquid chromatography (HPLC), the first application of CE in chiral separation was reported by Zare's group[3,4]. Using Cu(Ⅱ) complexes of L-histidine or aspartame as chiral selectors, 14 dansyl amino acids (Dns-AAs) were resolved. The authors observed a significant improvement in resolution when a micelle forming surfactant such as sodium dodecyl sulfate (SDS) was added to the electrolyte performing MEKC. The method was called as ligand-exchange micellar electrokinetic capillary chromatography (LE-MEKC). As a hybrid mode of possessing both the advantage of high enantioselectivity in ligand-exchange mechanism and the main advantages of MEKC, LE-MEKC allows the manipulation of the selectivity for large classes of neutral and charged compounds, making possible separation that otherwise are not feasible by using only the mode of LE or MEKC. Using this combined separation mode, hydroxy acids and dipeptides, as well as 16 positional and optical isomers of tryptophan derivatives could be optically resolved[5]. The same group also proposed a method for the determination of the critical micelle concentration (CMC) of anionic surfactants based on LE-MEKC principle[6].
