ISSN:
0935-6304
Keywords:
Capillary electrophoresis
;
Separation efficiency
;
Chiral separations
;
Fused silica surfaces
;
Adsorption
;
Non-ionic hydrophilic modifier
;
Polyvinylalcohols
;
Hydroxyethylcelluloses
;
Electrical modification of EOF
;
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Polyvinylalcohols (PVA) and hydroxyethylcelluloses (HEC) have been used as additives in cyclodextrin-modified capillary zone electrophoretic chiral separations of aromatic amines such as tocainide and its analogs in unpretreated 50 μm i.d. fused silica capillaries. The additives were used at low concentrations (〈0.05%) in common buffers, together with the γ-cyclodextrin as chiral selector. They reduce the electroosmotic flow, i.e. increase the migration times of the analytes in these chiral separations, and, moreover, considerably improve both peak symmetry and the widths of the peaks relative to migration time. In terms of the chromatographic theory of efficiency, more than 200000 theoretical plates can be achieved with unpretreated fused silica capillaries. This enhancement of efficiency arises because adsorptive “dynamic” coating with the hydroxylic modifier molecules suppresses adsorption of the analyte molecules by the capillary walls.The influence of field strength and buffer composition on the separation efficiency attainable with and without modifier in the buffers has also been investigated. Alternative experiments on the influence of analyte adsorption on efficiency have been performed by superimposing radial electric fields on the capillary to modify the ζ potentials. Although the EOF could be freely adjusted, it was not possible to obtain an improvement in efficiency comparable with that furnished by coating the adsorptive surface with PVA or HEC.
Additional Material:
10 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jhrc.1240151011
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