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  • Heat resistant surface deactivation  (1)
  • Profilanalyse  (1)
  • 1
    ISSN: 1612-1112
    Keywords: Glass capilary GC ; Heat resistant surface deactivation ; Testmixtures ; Polycyclic aromatic hydrocarbons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new method of making alkylpolysiloxane (OV 1, OV 101, OV 17, Dexsil 400, SE 52, SE 54) columns with high stability at temperatures above 300°C of both the stationary liquid itself (low bleeding) and of the surface deactivation (no tailing of polar solutes with extended use at temperatures beyond 250°C) is described. The best results were achieved on dealkalinized alkali glass but also on borosilicate surfaces which have been additionally HF treated before coating in both cases. The procedure can also be applied to leached alkali and borosilicate surfaces successfully. The best deactivations of the glass surface are attained in a two step procedure: firstly by treatment with gaseous HF/N2 mixture and secondly by simple heating of the coated and closed column at temperatures between 350° and 450°C for several hours. The tailing behaviour of such columns for polar solutes is considerably improved by this procedure as shown by test chromatograms. The procedure can also be applied to leached alkali and borosilicate surfaces successfully.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1618-2650
    Keywords: Analyse von Kohlenwasserstoffen, polycycl. in Klärschlamm ; Chromatographie, Gas ; Profilanalyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Es wird ein einfaches und selektives Anreicherungsverfahren für polycyclische aromatische Verbindungen angegeben (flüssig-flüssig-Verteilung: Dimethylformamid + Wasser + Cyclohexan; Chromatographie an Sephadex LH 20/Isopropanol; Filtration an Aluminiumoxid/Cyclohexan). Das Gemisch der polycyclischen aromatischen Kohlenwasserstoffe (= PAH) wird gas-chromatographisch an gepackten Hochleistungssäulen getrennt und die FID-Signale mit einem anfangs zugegebenen inneren Standard verglichen. Es wurden 18 Hauptkomponenten quantitativ ausgewertet. Die Variationskoeffizienten einer fünffachen Bestimmung derselben Probe lagen zwischen 1,6 und 11,3%. Die Nachweisgrenze des Verfahrens beträgt bei einer mittleren elektronischen Signalverstärkung in Abhängigkeit von der Retentionszeit 0,5–5 ng (für Benzo(a)pyren 1 ng). Die Charakterisierung der PAH mit 4–7 Ringen erfolgte mit einer GC-MS-Kombination, was für den Routinebetrieb aufgrund der großen Ähnlichkeit der PAH-Profile verschiedener Klärschlammproben nicht erforderlich ist.
    Notes: Summary A simple and selective method of enrichment of polycylic aromatic compounds is described (liquid-liquid-distribution with DMF + water + Cyclohexane; chromatography on Sephadex LH 20/isopropanol; filtration on aluminium oxide/cyclohexane). The fraction of polycyclic aromatic hydrocarbons (= PAH), separated gas-chromatographically using high performance columns, is evaluated by comparising the FID-signals with those of the internal standard added to the sample. Eightteen main components are evaluated. The variation coefficient of five analyses of the sample is in the range of 1.6–11.3%. The detection limit by moderate amplification depends on retention time of the PAH (0.5–5 ng; for benzo(a)pyrene 1 ng). As the PAH profiles of different samples of sludge are very similar, it is normally not necessary to characterize the PAH by mass spectrometry.
    Type of Medium: Electronic Resource
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