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  • 1
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 322-326 
    ISSN: 0935-6304
    Schlagwort(e): Capillary electrophoresis ; Enantiomer separation ; Drugs ; Loxiglumide ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Vancomycin has been used as chiral selector for the enantiomers separation of D, L-loxiglumide, a new drug proposed for the treatment of gastrointestinal pathology. The chiral selector, dissolved at very low concentration in the running buffer, filled only part of the capillary (polyacrylamide coated) and allowed chiral resolution in less than 12 min using a 50 mM phosphate buffer at pH 6. The partial separation technique allowed to obtain a detection limit of 0.5 μg/ml for each enantiomer avoiding the drop in sensitivity due to the strong UV absorption of vancomycin when present in the detector path. The effects of vancomycin concentration and buffer pH on enantiomers resolution have been studied in order to find the optimum experimental conditions for the chiral purity control of drug. The optimized method, using the internal standard, showed good reproducibility for both migration times and normalized peak area ratio and for linearity. Under the studied operating conditions it was possible to detect 0.2 % (w/w) of L-loxiglumide as a chiral impurity. Analysis of pharmaceutical preparations of D-loxiglumide did not reveal the presence of the impurity (L-isomer).
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0173-0835
    Schlagwort(e): Cyclodextrin modified - micellar electrokinetic chromatography ; Chiral separation ; Chrysene metabolism ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A γ-cyclodextrin (γ-CD) modified electrokinetic micellar capillary chromatography (MEKC) method was used for the enantiomer separation of a racemic trans-1,2-dihydro-1,2-dihydroxy-chrysene (chry-trans-1,2-diOH) mixture. The chiral resolution was strongly influenced by several important parameters: surfactant concentration and addition of organic modifier to the background electrolyte (BGE). An optimized electrophoretic system was used, consisting of the following conditions: 25 mM phosphate buffer, pH 7.8, 50 mM sodium dodecyl sulfate, 20 mM γ-CD, 7.4% V/V 2-propanol as BGE; the applied voltage, 18 kV, corresponded to 37 μA at a constant temperature of 25°C. This electrophoretic method was applied for monitoring the chry-trans-1,2-diOH enantiomer formation in a real sample, obtained from in vitro metabolic activation of chrysene by phenobarbital-ß-naphthoflavone-induced rat microsomes. The (+) and (-) enantiomers were identified by the racemate and the single enantiomer standard addition method and by spectra comparison with the synthetic compound. Under the experimental conditions used for chrysene activation, the (+) optical isomer was the prevailing form. The CD-MEKC system showed high reproducibility and selectivity, allowing a fast and interference-free analysis even of the in vitro metabolic sample extract, without any pretreatment.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 16 (1995), S. 1510-1518 
    ISSN: 0173-0835
    Schlagwort(e): Chiral separation ; Enantiomers ; Human serum transferrin Stereoselective interactions ; Capillary zone electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Enantiomers can be separated by using human serum transferrin as a chiral phase. With the help of the native protein we were able to separate enantiomers with high efficiency, using a low ionic strength 2-(N-morpholino)ethanesulfonic acid (MES) buffer, pH 6, in capillary zone electrophoresis. Tryptophan methyl, ethyl and butyl ester enantiomers - moving towards the cathode at pH 6 - were resolved by passing through an iron-free transferrin zone in coated capillaries. Since the isoelectric point of the iron-free transferrin is a little higher than 6, the protein zone is either not moving in the experiment or is slowly moving towards the anode. Under the simplest experimental conditions the highest resolution was obtained for the butyl ester enantiomers and the lowest for the methyl ester ones. By changing the experimental conditions, however, this order could be reversed. The results indicate that the lengths of the alkyl chains in the enantiomers have a significant effect on the resolution, i.e., on the interaction between the protein and the separands.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 0173-0835
    Schlagwort(e): Antibiotics ; Chiral separations ; Enantiomers ; Drugs ; Herbicides ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: A new glycopeptide antibiotic, MDL 63,246 (Hepta-tyr), of the teicoplanin family, has been evaluated in capillary electrophoresis for the resolution of chiral compounds of pharmaceutical and environmental interest. Electrophoretic separations were carried out in a polyacrylamide-coated capillary using the partial filling-counter current mode with aqueous-organic buffers in the pH range 4-6. Experimental parameters affecting resolution, such as antibiotic concentration, buffer pH, organic modifier type and capillary temperature, were studied. The Hepta-tyr antibiotic exhibited a high enantiorecognition capability towards the studied compounds at very low concentrations (1-2 mg/mL). The optimum experimental conditions were achieved by using a buffer at pH 5 containing acetonitrile at 25°C.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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