Chiral electromigration methods

Simo, C., Barbas, C., and Cifuentes, A., Chiral electromigration methods in food analysis. Electrophoresis, 24, 2431, 2003. 

Novotny, M., Soini, M., and Stefansson, M., Chiral separation through capillary electromigration methods, Anal. Chem., 66, 646A, 1994. 

Hernindez-Borges, J., Rodriguez-Delgado, M. A., Garcia-Montelongo, F. J., and Cifuentes A., Chiral analysis of pollutants and their metabolites by capillary electromigration methods. Electrophoresis, 26, 3799, 2005. 

Wistuba, D, A Bogdanshi, KL Larsen and V Schuring (2006). (5-cyclodextrin as novel chiral probe for enantiomeric separation by electromigration methods. Electrophoresis, 27,4359-4363. 

In the enantioseparation by electromigration methods different chiral selectors (such as cyclodextrins and their derivatives, cellulose, bile acids, or chiral surfactants, for instance, Ai-deoxycarbonylvaline) are added to the running buffer [9-11]. Cyclodextrins may also be incorporated in the silica bed or may be mixed with other selectors [10]. Many investigations revealed that the magnitude of enantioseparation depends not only on the concentration of chiral selector in the buffer but also on the addition of organic solvent and on its concentration. 

The first section of the book explores emerging novel aspects of HPLC and related separation methods based on the differential velocity of analytes in a liquid medium under the action of either an electric field (capillary electromigration techniques) or a gravitational field (field-flow fractionation). The section focusing on applications highlights four significant areas in which HPLC is successfully employed chiral pharmaceutical, environmental analysis, food analysis, and forensic science. 

Chromatography is one of the most important methods for direct studies of molecular and chiral recognition by CyDs. Today it has split into several branches, e.g. gas chromatography, GC, high-performance liquid chromatography, HPLC, and capillary electrophoresis and other electromigration techniques, that enable us not only to detect the recognition but also to estimate the complex stoichiometry and formation constant and, consequently, the enthalpies and entropies of complex for-... 

In 1992 Mayer and Schurig showed for the first time the possibility of enantioseparations in open tubular capillaries modified with a permethylated CyD derivative. This technique was used later with different chiral selectors but did not mature to become the method of choice for CEC enantioseparations, most likely due to the following conflict inherent in this technique. For a separation which occurs on the mobile phase/stationary phase interface and not in the bulk solution, retention of the analyte on the capillary wall (chiral stationary phase) is necessary for achieving a separation. On the other hand, any retentive analyte-capillary wall interactions are associated with a drastic decrease in peak efficiency in capillary electromigration techniques. However, this study stimulated research in both capillary enantioseparation techniques and in the use of CyD-based CSPs for CEC enantioseparations. 

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