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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 10 (1977), S. 181-187 
    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.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 10 (1977), S. 250-255 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In most capillary GCL columns the film thickness is almost always the same. In addition to column dimensions, liquid phase and support characteristics, however, the film thickness of a column is of great importance and should be adjusted for the specific problem. Dependence of retention, separation efficiency, inertness, capacity, and thermal stability on film thickness is empirically shown for a 100-fold (1∶100) thickness range. In conclusion, directions are given for determining the appropriate film thickness for the different types of sample and analytical tasks.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 149-155 
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; Capillary, glass ; Preparation of apolar columns ; Ba CO3 procedure optimized for thermostability acid/base behaviour and efficiency ; New, quantitative testing procedure ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: As an extension of previous reports, the barium carbonate procedure has been optimized in detail for the preparation of apolar columns. The aim was to produce optimum overall column characteristics, and to maintain them unchanged under the prolonged influence of the highest possible temperature. The main parameters under optimization were glass variety, leaching of glass surface with aqueous HCl, and amount of barium carbonate deposited, while deactivation and coating were kept constant. The basic column characteristics were adsorption properties and thermostability of deactivation, acid/base behaviour and separation efficiency. They were determined by a new, quantitative testing procedure. Intense leaching was able to eliminate almost totally the differences between glass varieties and to create a well-defined glass surface. While untreated glass, leached glass, and barium carbonate treated glass showed specific weak points in the respective column quality, the combination of leaching and barium carbonate treatment yielded the highest and most stable quality. Some technical modifications of the preparation procedure are described, including deactivation in the gas phase, and use of pentane as a solvent for static coating.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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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
    Journal of High Resolution Chromatography 2 (1979), S. 31-35 
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Surface deactivation, silylation ; Inertia stable to 350° ; Free acids and bases, simultaneous injection ; On-column injection ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A deactivation procedure is described based on a published method using hexamethyldisilazane in the gas phase. In addition to unusually high inertia and thermostability, the method produces truly neutral columns which allow simultaneous analysis of moderately strong free acids and bases. The silylated columns show their full potential only with on-column injection. Preliminary experimental directions are given; more elaborate directions will become available after extended optimization work.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 57-64 
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; Capillary, glass ; Splitless injection, basis of ; Use for any sample ; Optimization ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Splitless injection is based on the solvent effect as a mechanism condensing large vapour clouds down to infinitely shortened bands. The effect is controlled by the parameters column temperature, volatility and amount of solvent, and rate of injection. By properly selecting the variables the effect can easily be optimized for any combination of sample and column. It is the purpose of this paper to provide the mechanistic understanding as required for this optimization, as well as some rules for the experimental realization. Potentialities and limitations of splitless injection are discussed, and the role of the solvent effect in on-column injection is emphasized.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Sozial- und Präventivmedizin 9 (1964), S. 14-25 
    ISSN: 1420-911X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Nous avons étudié l'absorption, par un liquide tamponné similaire à la salive, de la nicotine («alcaloïdes totaux») contenue dans la fumée. Il s'avère que les tabacs réagissent différemment suivant le genre, de sorte que ni le taux de nicotine du tabac, ni la quantité totale de nicotine retrouvée dans la fumée condensée («total particulate matter»), ne peuvent servir de base valable pour juger l'effet physiologique de cigarettes différentes. La nicotine libre (sous forme de vapeur) est facilement absorbée par un liquide tamponné tel que la salive. La pression de vapeur de la nicotine étant plus forte (à 37°C) dans une fumée à pH élevé, davantage de nicotine se trouve donc dans la phase-vapeur. En effet, la «salive», après contact avec une fumée de pH élevé, contient une plus forte proportion de la nicotine qu'après contact avec une fumée de pH bas. La surface en contact avec la fumée (profondeur de l'inhalation), ainsi que la durée du contact, entrent également en ligne de compte. En outre, la longueur du mégot joue un rôle important, du fait qu'une quantité considérable de nicotine peut être retenue lors du passage de la fumée et vaporisée à nouveau lorsque la zone de combustion s'approche.
    Notes: Zusammenfassung Wie die vorliegenden Untersuchungen zeigen, ist eine Beurteilung der physiologischen Wirkung verschiedener Cigaretten sowohl auf Grund des im verrauchten Tabak enthaltenen als auch auf Grund des insgesamt im Rauch vorgefundenen Nikotinsäußerst fragwürdig. Die Nikotin-Absorption beim Rauchen wird in wesentlichem Maße bestimmt: 1. Durch dasphysikalisch-chemische Verhalten des Nikotins im Rauch, das weitgehend vom pH-Wert beeinflußt wird. 2. Durch dieRauchgewohnheit (Inhalationstiefe, Verweilzeit des Rauches), welche das Ausmaß und die Dauer des Kontaktes zwischen dem Rauch und den absorbierenden Oberflächen bestimmt. Die pro Rauchzug zur Verfügung stehende Nikotinmenge hängt offensichtlich in hohem Maße von derStummellänge ab, infolge der beachtlichen Nikotinmenge, die vom Tabakstummel aus dem durchströmenden Rauch absorbiert werden kann.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 10 (1977), S. 625-625 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusion Based on the above-mentioned fundamental advantages, gums should be considered the ideal phases for capillary GLC. Therefore, we strongly recommend users to select a gum whenever it is not precluded because of critical polarity/selectivity requirements. On the other hand we emphasize the great need for a much wider choice of gum phases. We are convinced that developing new and especially, more polar, gum phases is one of the best services that can be rendered to our analytical field. It is our hope that this may be a challange for some polymer scientists.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 9 (1976), S. 509-512 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary According to the experimental evidence reported in this paper, the inner surface of tubings of Pt and other noble metals may, under certain conditions, become strongly active. The activity may increase to such an extent that severe band broadening, tailing, and even total disappearing of organic substances of various classes (not just polar ones) are caused. Typically, noble metals constantly adapt their surface to the actual ambient conditions. It is not possible to maintain their surface in a given, preselected state. The most significant variable parameter influencing the surface is the nature of the effluent from a GC column. Upon column interchange, drastic changes in the surface characteristics of noble metal tubings can be observed. In contrast, a glass surface can be permanently inactivated and is not affected by varying effluents when columns are interchanged.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Chromatographia 8 (1975), S. 423-433 
    ISSN: 1612-1112
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The fact that gas chromatography on glass capillary columns is far from being exploited to its full potential is due to two main reasons: widespread disappointment in poor quality columns and insufficient know-how in the application technique. In order to provide facts about the true situation, general information is given here about performance and durability of a large number of glass capillary columns currently in routine use, some of these for years, at various laboratories. It is emphasized that glass capillaries, as well as the related chromatographic technique and equipment, cannot be successfully considered and handled using the experience gained from packed columns, but should be given particular consideration. The majority of existing glass capillary columns are used for the analysis of complex mixtures. In many instances even extreme separation efficiency may not achieve sufficient resolution. In these cases ancillary techniques may fill the remaining gap. Practical applications of three such techniques, the principles of which are not new, are described; namely, multiple detection, odour analysis, and two-dimensional analysis. A new technique for the introduction of large gaseous samples onto capillary columns is presented with a detailed discussion of its mechanism.
    Type of Medium: Electronic Resource
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