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  • 1
    Publication Date: 1983-04-01
    Print ISSN: 0009-5893
    Electronic ISSN: 1612-1112
    Topics: Chemistry and Pharmacology
    Published by Springer
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  • 2
    Publication Date: 1981-01-01
    Print ISSN: 0016-1152
    Topics: Chemistry and Pharmacology
    Published by Springer
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  • 3
    Publication Date: 1980-01-01
    Print ISSN: 0016-1152
    Topics: Chemistry and Pharmacology
    Published by Springer
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 17 (1983), S. 215-220 
    ISSN: 1612-1112
    Keywords: Liquid chromatography ; Dead time determination ; Non-aqueous eluents ; Stationary phase formation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Anhydrous alcohol eluents are partly sorbed on bonded octadecyl phases. The sorbed fraction can best be described as a double layer. The length of the alcohol carbon chain determines the volume of the sorbed eluent layer and, consequently, that of the bulk eluent. Thus, column dead-time depends on the molecular size of the eluent. The column dead-time in such systems can be determined via mathematical linearization of the In (capacity factor) versus carbon number function only if (a) the solute chain length is below that of the bonded alkyl chain, (b) the data are very precise, (c) at least five data points are included.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 305 (1981), S. 405-408 
    ISSN: 1618-2650
    Keywords: Analyse freier Radikale ; Chromatographie, HPLC ; Chemisch gebundene Umkehrphasen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Freie organische Radikale lassen sich im reverse-phase-Verfahren an einer chemisch gebundenen Octadecylphase (Micro Pak CH 10) mit Methanol/Wasser als Eluens trennen. Die Probenkomponenten üben eine starke Wechselwirkung mit der stationären Phase aus. Es ist möglich, Radikale zu trennen, deren Struktur sich nur um eine Doppelbindung unterscheidet, oder die anstelle einer Ketofunktion eine Alkoholgruppe tragen. Die Radikale werden bei dieser Trennung nicht verändert. Die Nachweisgrenzen liegen im allg. im Bereich von 10−6 bis 10−7 Mol/l.
    Notes: Summary Free organic radicals were separated on a chemically bonded octadecyl phase (Micro Pak CH 10), using mixtures of methanol and water as mobile phase. It was found that the radicals strongly interact with the stationary phase. It is possible to separate radicals with such differences in structure as introduction of a double bond or substitution of a keto group by an alcohol function. The radicals are not altered during separation. Limits of detection are generally in the range of 10−6 to 10−7 Mol/l.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 301 (1980), S. 417-425 
    ISSN: 1618-2650
    Keywords: Analyse von Dimethyltrisulfid ; Massenspektrometrie ; Diskussion der Spektren
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary The mass spectra obtained by electron impact ionization (EI) of dimethyltrisulfide, both at constant sample pressure and during elution from a GC column, are essentially identical, with the molecular ion Me2S 3 + providing the basis peak. Masses heavier than the molecular ion are not observed. Chemical ionization, using nitrogen, methane or isobutane, gives rise to numerous ions of larger mass than that of the molecular ion. Particularly characteristic are sulfonium type structures Me3S n + , with n=3–6. In addition, radical cations of the type Me3SnCH 2 + and protonated trisulfide, Me2S3H+, are observed, even with N2 as ionizing gas, together with a variety of ions of lower hydrogen content. Further, a large number of ion types of lower mass than the parent molecule are formed. The mass distribution of ions in the spectrum is found to be highly dependent on the partial pressure of dimethyltrisulfide in the ion source. These phenomena were investigated and accounted for semiquantitatively.
    Notes: Zusammenfassung Dimethyltrisulfid liefert nach Elektronenstoßionisation bei konstantem Probendruck und bei GC-Probeneinlaß im wesentlichen identische Massenspektren. Das Molekülion Me2S 3 + stellt dabei den Basispeak dar. Größere Massen als die des Molekülions wurden nicht beobachtet. Bei chemischer Ionisation unter Verwendung von Stickstoff, Methan oder Isobutan als Reaktantgas entstehen zahlreiche Ionen mit höherer Masse als der des Molekülions. Charakteristisch sind hierbei sulfoniumartige Strukturen Me3S n + mit n=3–6. Daneben beobachtet man Radikalkationen des Typs Me2SnCH 2 + und protoniertes Trisulfid Me2S3H+ auch bei Ionisation mittels N2 sowie Ionenarten mit einem geringeren Wasserstoffgehalt. Weiterhin wird eine größere Anzahl von Ionenarten gebildet, deren Massen kleiner sind als die des Stammoleküls. Die Massenverteilung der Ionen im Spektrum hängt außerordentlich stark vom Partialdruck des Dimethyltrisulfids in der CI-Quelle ab. Diese Abhängigkeiten wurden semiquantitativ untersucht und dargestellt.
    Type of Medium: Electronic Resource
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