Electromigration, enantioseparation

Chankvetadze, B. (1999). Recent trends in enantioseparations using capillary electromigration techniques. Trends Anal. Chem. 18, 485—498. 

B Chankvetadze, G Blaschke. Enantioseparations in capillary electromigration techniques recent developments and future trends. J Chromatogr A 906 309-363, 2001. 

Chankvetadze, B. Enantioseparation of chiral dmgs and current status of electromigration techniques in this field, /. Sep. Sci. 2001, 24, 691-705. 

In this context, the on-hne coupling of CE with MS has evolved into an efficient, sensitive and selective technique for the chiral analysis of drugs. This chapter does not intend to cover aU the recent developments in the application of electromigration approaches coupled with conventional detection techniques such as UV, electrochemical, fluorescence or LIE [1, 2] for the enantioselective analysis of drugs. Moreover, achiral CE-MS apphcations have been summarised in recent reviews and these can be consulted for a more systematic coverage of the field [3-5]. This chapter will therefore focus on the electrophoresis-based enantioseparation technique coupled with mass spectrometry. 

In summary, capillary electromigration techniques possess real potential to compete successfully with chromatographic methods for analytical enantioseparations. However, the future will show if these techniques may be also used for obtaining pure enantiomers on a micropreparative scale. 

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. 

Chankvetadze, B. Blaschke, G. Enantioseparations using capillary electromigration techniques in non-aqueous buffers. Electrophoresis 2000, 21, 4159 178. 

Chankvetadze B, Endiesz G, Blaschke G (1994) About some aspects of the use of chaiged cyclodextrins for capillary electrophoretic enantioseparations. Electrophoresis 15 804-807 Chankvetadze B (1999) Recent trends in chiral separations using capillary electromigration techniques. TrAC (Trends Anal Chem) 18 485 98... 

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. 

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