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  • 1
    Electronic Resource
    Electronic Resource
    Enantioseparation of amino acids and dipeptides using vancomycin as chiral selector in capillary electrophoresis (1996)
    Weinheim : Wiley-Blackwell
    Electrophoresis 17 (1996), S. 1938-1944 
    Details
    ISSN: 0173-0835
    Keywords: Capillary electrophoresis ; Enantiomers ; Vancomycin ; Amino acids ; Dipeptides ; Optimization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Vancomycin was applied as chiral selector for the enantiomeric separation of derivatized amino acids and dipeptides. The influence of vancomycin concentration, pH and presence of 2-propanol in the buffer were examined in order to find optimal separation conditions. Optimization was by factorial design. Further, chiral separation of derivatives prepared with three different reagents was compared. These reagents were 9-fluorenylmethyl chloroformate (FMOC), 2-(9-anthryl)ethyl chloroformate (AEOC) and dansyl chloride (dansyl). Optimum resolution was at high vancomycin concentrations, while optimum efficiency was at low vancomycin concentrations. As a consequence of the very high enantioselectivity of vancomycin, the vancomycin concentration below the amount necessary for maximal resolution can be used. Separation efficiency was relatively low, and this could be attributed to adsorption of the selector at the capillary wall. Three factors led to decreased adsorption: application of a pH above the zero mobility pH value, low vancomycin concentrations and the presence of 2-propanol. For amino acids, the resolutions of the different derivatives were: dansyl 〉 AEOC 〉 FMOC, while for dipeptides, the highest selectivity was with AEOC.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150171222
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  • 2
    Electronic Resource
    Electronic Resource
    Chiral separation of DL-peptides and enantioselective interactions between teicoplanin and D-peptides in capillary electrophoresis (1997)
    Weinheim : Wiley-Blackwell
    Electrophoresis 18 (1997), S. 943-949 
    Details
    ISSN: 0173-0835
    Keywords: Capillary zone electrophoresis ; Enantiomers ; Macrocyclic antibiotics ; Teicoplanin ; Dipeptides ; Tripeptides ; Optimization ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Teicoplanin has been evaluated as a selector for enantioseparation of di- and tripeptide derivatives in capillary electrophoresis. Separation variables such as type of buffer, pH, concentrations of teicoplanin and organic modifier were examined. Optimal separation conditions were obtained by means of factorial design experiments. The effects of teicoplanin concentrations below and above its critical micellar concentration (CMC) and of acetonitrile (ACN) on the separation were demonstrated. The use of a high concentration of ACN resulted not only in increased selectivity, but also in improved separation efficiency. Electroosmotic flow was observed to be largely independent of the concentrations of teicoplanin under the optimized conditions. Good repeatability of migration times was obtained. The interactions between teicoplanin and D and L peptides were studied, and it was found that, for some peptides, teicoplanin exhibited enantioselective interaction only with the D-form. Somewhat lower separation efficiencies were thus observed for the strongest interacting (D-form) peptides. Chiral separation of 15 DL-peptide derivatives was achieved in less than 10 min.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elps.1150180615
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