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  • 1
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Wir führen das geringe Vertrauen vieler Fachleute der Kapillar-GC gegenüber auf folgende Ursachen zurück: Erstens ist die Mehrzahl der verwendeten Kapillarsäulen von ungenügender Qualität; hochwertige Säulen sind jetzt erhältlich. Zweitens liefern auch die besten Säulen die erwarteten Ergebnisse nur, wenn gewisse apparative und methodische Voraussetzungen erfüllt sind. Die vorliegende und nachfolgende Arbeiten sollen Lücken dieser Art schließen helfen. Prinzip, Anwendungsgebiete und Technik der Direkteinspritzung (Splitlose Injektion) auf Kapillarsäulen werden eingehend besprochen. Es wird gezeigt, daß z. B. Benzol in Pentan trotz der geringen Flüchtigkeitsdifferenz bis zur Verdünnung von 1∶108 (10 ppb) nachweisbar ist, wenn verbreitete apparative und methodische Fehler behoben werden. Eine Parallelanalyse von Tabakaroma und Tabakrauch illustriert die große Anwendungsbreite der Direkteinspritzung.
    Abstract: Résumé Nous pensons que le peu de confiance que beaucoup de spécialistes placent en la CG sur colonne capillaire doit étre dû à diverses causes. D'une part, la plupart des colonnes capillaires employées sont d'une qualité insuffisante alors que l'on peut maintenant obtenir des colonnes de haute qualité. D'autre part, même avec les colonnes de la meilleure qualité on peut obtenir le résultat désiré seulement quand certaines conditions sont remplies en ce qui concerne l'appareillage et les méthodes employées. Le présent travail (ainsi que d'autres qui seront publiés ultérieurement) doit permettre de combler ces lacunes. Le principe, les possibilités d'application et la technique d'injection directe (sans diviseur) sur des colonnes capillaires sont étudiés en détai. On montre, par exemple, que le benzène dans le pentane, en dépit de leur faible différence de volatilité, peut être détecté à une dilution pouvant aller jusqu'à 1∶108 (10 ppb) si l'on élimine certaines erreurs très fréquentes et dues à l'appareillage et aux méthodes. Une analyse parallèle de l'arôme et de la fuméc de tabac permet de montrer les grandes possibilités d'application de l'injection directe.
    Notes: Summary We are attributing the lack of confidence of many specialists towards capillary GC to two reasons. First, most of the capillary columns used are of insufficient quality; but columns with high performance are now available. Secondly, even optimum columns will only supply the expected results if certain conditions in instrumentation and methodology are met. The present paper, to be followed by subsequent publications, is intended to help to bridge such gaps. The principle, application, and technique of direct sample injection (without split) on capillary columns is discussed in detail. It is shown that e.g. benzene in pentene, in spite of the small difference in volatility, can be detected in concentrations as low as 1∶108 (10 ppb) if common errors in instrumentation and technique are climinated. A parallel analysis of tobacco flavour and tobacco smoke illustrates the wide range of application of direct injection.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The present second report on the preparation of glass capillary columns, based on producing a crystal layer of barium carbonate on the internal capillary surface, completes the information given in the first report mainly in three directions. First, more practical experience with long term use is presented, showing this column type to be very promising because of universality, durability, simplicity, and efficiency. Second, more insight is given into the underlying processes, as well as into the produced effects. A new aspect concerns the double function of the barium carbonate layer, namly roughening the internal column wall and covering the catalytically active silica surface. Third, more elaborate procedures reducing the particle size of barium carbonate crystals are discussed. On finer particles more homogeneous films, yielding higher separation efficiency, are obtained. Detailed practical directions to new procedures are given.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 4 (1971), S. 422-424 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The authors report on quality tests for capillary columns, which are carried out in their laboratory since a few years. Besides the known test values such as separation number, polarity, adsorption, film thickness, is the significance of the acidity of a column investigated. The acidic or basic behaviour of a column can be determined with considerable sensitivity by a comparison of the peak areas obtained by analyzing the pair 2,6-dimethylaniline and 2,6-dimethylphenol. These test substances have been selected because they show similar retention characteristics on columns of any polarity, similar deviations from the neutral behaviour, lowest possible tendency to form hydrogen bonds, and practically the same response factors for flame ionization and thermal conductivity detectors. The test procedure is described.
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  • 4
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface deactivation, persllylation ; Discussion of variable parameters ; Suggested practical procedure ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Leaching compared to etching ; Leaching by 20% HCI at 240°C ; Metal ions eliminated from glass surface ; Silica layer formed on leached surface ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 17 (1983), S. 481-485 
    ISSN: 1612-1112
    Keywords: Polarity ; Stationary phases ; Temperature dependence ; GC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary It is not commonly appreciated that retention indices are temperature dependent. It is even less common to express this fact in more practical terms by saying that polarity is temperature dependent. Although the meaning of both statements is identical, we believe the second to be particularly relevant, since the majority of practical gas chromatographers tends to handle polarity as an invariable characteristic of a stationary phase. The variability of polarity with temperature is the major source of inadequate reproducibility of exact finger-printing, this particularly when gc/ms traces have to be compared to those obtained by pure gc. On the other hand, the temperature dependence provides a practical means to optimize the polarity of a given column for a given analysis. Film thickness is an essential parameter in this context because of its influence on column temperature and, therefore, on column polarity.
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Testing uncoated columns ; Test with precolumn ; Adsorption, and acid/base effects ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Sample preparation ; Closed loop stripping analysis ; Charcoal adsorbent filter ; Overcoming contamination ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns ; Static coating ; Vacuum sources ; Coating solvent ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 33 (1950), S. 1070-1079 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Es wird die Synthese der beiden diastereomeren 7,8-Bis-acetyl-amino-6-keto-nonansäuren (XI), ausgehend von Cyclohexanon, Nitromethan und Acetaldehyd, beschrieben. Die beiden als Zwischenprodukte auftretenden diastereomeren 1-Nitro-1-cyclohexenyl-2-acetyl-amino-propane (VIII) lassen sich ineinander überführen, so dass die Synthese stereochemisch kontrolliert werden kann.
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