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  • 1
    ISSN: 1612-1112
    Keywords: Exclusion chromatography, enzymes ; Exclusion chromatography, proteins ; Liquid chromatography, amino acids ; Silica, bulk modified ; Silica, surface modified
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary 1,2-dihydroxy-3-propoxypropyl (HPPS), 1-amino-2-hydroxy-3-propoxypropyl (AHPS) and 1-aminoethyl-3-aminopropyl (AEAPS) silica were synthesized by means of both a surface modification procedure (I) and a bulk modification procedure (II). Method (I) gave a surface concentration, α, of functional groups of 2–3 μmole/m2, whereas method (II) gave values up to 5 μmole/m2. Retention times, peak asymmetries and plate heights of thiamine and ascorbic acid eluted with aqueous buffer solutions ranging from pH 5.3 to 9.2 gave only a±5% variation over periods of 12 hours and more. The recoveries of selected enzymes and proteines examined under static and dynamic conditions were between 60% and 100% depending on the functional group of the packing and on the solute. With HPPS silica, which showed the least adsorption and denaturing effects, separation of biopolymers depended on a size exclusion effect in the relative molecular mass range 10,000 to 80,000 and could be achieved within 10 min.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Modifiziertes Siliciumdioxid mit chemisch gebundenen alkoholischen Hydroxylgruppen an der Oberfläche wurde einmal als polare stationäre Phase in der Flüssig-Fest-Chromatographie (LSC), zum anderen als Trägermaterial in der Gel-Chromatographie getestet. In der LSC ergab sich, daß die Kapazitätsfaktoren von gelösten Komponenten nahezu unabhängig vom relativen Wassergehalt der unpolaren mobilen Phase sind. In der Gel-Chromatographie konnten in Wasser gelöste Polyäthylenglycole fraktioniert werden, ohne daß eine irreversible Adsorption an der porösen Matrix auftrat.
    Notes: Summary Chemically modified silica with alcohol hydroxyl groups was tested as a polar stationary phase in Liquid Solid Chromatography (LSC) and as a hydrophilic support in Gel Chromatography. In LSC the capacity factors of solutes were almost independent of the relative water content of the non-polar mobile phase. Furthermore, polyethylene glycols dissolved in water could be efficiently fractionated without irreversible adsorption effects on columns packed with this material.
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  • 3
    ISSN: 1434-4483
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Description / Table of Contents: Summary A method for the determination of accumulated temperatures as developed by Pallmann, Eichenberger and Hasler is described. The method depends on the fact that the reaction speed for the inversion of acidified sugar solution is temperature dependent. The speed of inversion can be controlled by measuring polarimetrically the change in the angle of rotation. The practical application of this method in bioclimatology and soil science studies is described in view of our own experience. The three application examples given show that the method is suitable for obtaining satisfactorily usable results in the simplest possible manner, and with the minimum of expense.
    Notes: Zusammenfassung Es wird das von Pallmann, Eichenberger und Hasler entwickelte Verfahren der Temperaturmessung beschrieben, welches auf der Abhängigkeit der Inversionsgeschwindigkeit einer angesäuerten Zuckerlösung von der Temperatur beruht. Die Inversionsgeschwindigkeit kann durch polarimetrische Messung der Drehwinkel kontrolliert werden. Die praktische Anwendung der Methode wird anhand eigener Erfahrungen beschrieben. Mit drei Anwendungsbeispielen konnte gezeigt werden, daß mit Hilfe dieser Methode auf einfachstem Wege und mit geringstem Kostenaufwand biologisch stichhaltige Ergebnisse zu erzielen sind.
    Type of Medium: Electronic Resource
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