title: Enantioseparation of dipeptides by capillary electrochromatography on a teicoplanin aglycone chiral stationary phase.
abstract: This work deals with investigations on the enantioseparation of glycyl-dipeptides by capillary electrochromatography (CEC) on a capillary packed with teicoplanin aglycone immobilized on 3.5 microm silica gel. The results were compared to those obtained with micro-HPLC using the same chiral stationary phase. Polar organic and reversed-phase mode were checked, whereby the latter showed better results. Out of 12 glycyldipetides investigated, all compounds showed baseline separation with Rs values up to 20. Plate numbers were in the range of 10,000-300,000/m. The choice of organic modifier was found to be crucial. While methanol increased retention time, acetonitrile reduced it. A ternary mixture of ethanol-acetonitrile-aqueous triethylamine acetate solution pH 4.1 was found to be a useful compromise, providing excellent resolution with retention times less than 25 min. Efficiency and resolution were generally found to be higher in CEC than with micro-HPLC.
authors.affiliation: Institute of Pharmaceutical Chemistry and Pharmaceutical Technology, Karl-Franzens University, Universitätsplatz I, A-8010 Graz, Austria. schmidm@uni-graz.at
authors.forename: Martin G
authors.initials: MG
authors.lastname: Schmid
authors.forename: Nina
authors.initials: N
authors.lastname: Grobuschek
authors.forename: Verena
authors.initials: V
authors.lastname: Pessenhofer
authors.forename: Andrea
authors.initials: A
authors.lastname: Klostius
authors.forename: Gerald
authors.initials: G
authors.lastname: Gübitz
mesh_terms: D002851:Chromatography, High Pressure Liquid; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D004151:Dipeptides / Q000302:isolation & purification*; D013237:Stereoisomerism; D017334:Teicoplanin / Q000737:chemistry*
chemical_list: D004151:Dipeptides; D017334:Teicoplanin