Enantioselective capillary electrochromatography

This review provides an overview of the literature published to date on macrocyclic antibiotics exploited for enantioselective separations in high-performance liquid chromatography (HPLC). It was not intended as a comprehensive issue on the applications of such antibiotics in sub- and supercritical fluid chromatography (SFC), thin layer chromatography (TLC), capillary electrophoresis (CE), and capillary electrochromatography (CEC). A number of structural properties of the most important macrocyclic antibiotics applied in HPLC enantioseparations are listed in Table 2.1. 

Karlsson, C., Wikstrom, H., Armstrong, D. W, and Owens, P. K. (2000). Enantioselective reversed-phase and non-aqueous capillary electrochromatography using a teicoplanin chiral stationary phase.. Chromatogr. A 897(1-2, 3), 349-363. 

Lammerhofer, M., Tobler, E., Zarbl, E., Lindner, W., Svec, E, and Frechet, J. M. J. (2003). Macroporous monolithic chiral stationary phases for capillary electrochromatography new chiral monomer derived from cinchona alkaloid with enhanced enantioselectivity. Electrophoresis 24, 2986-2999. 

The use of antibiotic-based CSPs has been reported in capillary electrochromatography (CEC) for chiral resolution [60]. Teicoplanin CSP covalently bonded to silica gel was used to resolve the enantiomers of tryptophan and dinitrobenzoyl leucine by CEC [61]. Good levels of enantioselectivity were obtained with optimized separations. Vancomycin covalently bonded to silica gel was also evaluated in CEC for the chiral resolution of thalidomide and jS-adrenergic blocking agents under all the three mobile phase modes. The... 

Capillary electrochromatography is a more complicated system than CE and HPLC due to the combination of both electrophoretic and chromatographic transport mechanisms. It is difficult to define an effective selectivity (separation factor) as in the case of general chromatography or general electrophoresis. To better illustrate the interactions that control selectivity, we defined a relative selectivity a,. =. tjt 2), and postulated a model that illustrates the effect of separation parameters on the enantioselectivity [10]. 

Andre, C., Berthelot, A., Thomassin, M., Guillaume, Y. C. (2006). Enantioselective aptameric molecular recognition material design of a novel chiral stationary phase for enantioseparation of a series of chiral herbicides by capillary electrochromatography. Electrophoresis 27, 3254-3262. 

Li HF, Zeng HL, Chen ZF, Lin JM (2009) Chip-based enantioselective open-tubular capillary electrochromatography using bovine serum albumin-gold nanoparticle conjugates as the stationary phase. Electrophoresis 30 1022-1029... 

The chiral SO is coated to the capillary wall. This technique is known as open-tubular electrochromatography (OT-EC) )5(X)1. Enantioselective OT-EC methods have been described for CDs 1277), proteins ).501), polysaccharides )5021 and terguride [503] as chiral selectors. The main disadvantage is the low loading capacity, and therefore this technique has not gained high popularity. 

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