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  • 1
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Aldoses, ketoses and uronic acids were derivatized with p-aminobenzoic acid and separated as their borate complexes by capillary zone electrophoresis, using a capillary tube of fused silica containing 150 mM borate buffer, pH 10.0, as carrier. The electrophoretic mobilities of 22 carbohydrates were determined and found to increase with increasing stability of the borate complexes formed. Besides the number of hydroxyl groups and the presence of substituents, complex stability depended most strongly on the configuration of the three vicinal hydroxyl groups at C2, C3 and C4. On-column UV monitoring at 285 nm allowed the detection of glucose with a lower mass detection limit of 15 fmol and a concentration sensitivity of 4 μM. Reproducible quantification of carbohydrates was achieved at least in the concentration range of 0.1-10 mM in reaction solutions by the relative peak area method, using cinnamic acid as internal standard. The method was applied successfully to the determination of the monosaccharide composition of polysaccharides extracted from Radix althaeae.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 0173-0835
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Aldoses, ketoses and uronic acids were derivatized successfully within 15 min at a temperature of 90°C by reductive amination with 4-aminobenzonitrile. Subsequently, the derivatives were separated as their borate complexes by capillary zone electrophoresis, using 175 mM borate buffer, pH 10.5, as carrier. The electrophoretic mobilities were determined by the complex stability, which was found to depend on the number of hydroxyl groups on any given carbohydrate derivative, the presence of substituents, and most strongly on the configuration of the vicinal hydroxyl groups at C-3 and C-4 in aldoses and uronic acids, and with regard to ketoses on those at C-4 and C-5. Time of analysis could be reduced considerably by the use of micellar electrokinetic chromatography, which separated 4-aminobenzonitrile sugar derivatives on the basis of their differential partitioning into an electroendosmotically driven aqueous phase and into sodium dodecyl sulfate micelles. Optimum resolution was achieved with a Tris-phosphate buffer, pH 7.5, containing 100 mM of sodium dedecyl sulfate. The method made it possible to resolve several carbohydrates which had not been resolved successfully by means of capillary zone electrophoresis, such as glucose and fructose. Moreover, separation selectivity could be adjusted by varying the capillary temperature. Finally, on-column UV monitoring at 285 nm allowed the detection of glucose with a lower mass detection limit of 1 fmol and a concentration sensitivity of 0.3 μM.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    ISSN: 0173-0835
    Schlagwort(e): Capillary electrophoresis ; Proteins ; Peptides ; Derivatized polystyrene nanoparticles ; Coated capillary ; Hydrophilic surface ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: High-resolution capillary electrophoretic separation of proteins and peptides was achieved by coating the inner wall of 75 μm ID fused-silica capillaries with 40-140 nm polystyrene particles which have been derivatized with α-ω-diamines such as ethylenediamine or 1, 10-diaminodecane. A stable and irreversibly adsorbed coating was obtained upon deprotonation of the capillary surface with aqueous sodium hydroxide and subsequent flushing with a suspension of the positively charged particles. At pH 3.1, the detrimental adsorption of proteins to the capillary inner wall was suppressed efficiently because of electrostatic repulsion of the positively charged proteins from the positively charged coating which enabled protein separations with maximum efficiencies of 400 000 plates per meter. A substantial improvement of separation efficiency in particle-coated capillaries was observed after in-column derivatization of amino functionalities with 2,3-epoxy-1-propanol, resulting in a more hydrophilic coating. Five basic and four acidic proteins could be separated in less than 7 min with efficiencies up to 1 900 000 theoretical plates per meter. Finally, coated capillaries were applied to the high-resolution analysis of protein glycoforms and bioactive peptides.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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