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  • 1
    Electronic Resource
    Electronic Resource
    Synthesen in der Biotinreihe. I. Derivate der 7,8-Diamino-6-Keto-nonansäure (1950)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 33 (1950), S. 1070-1079 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19500330437
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  • 2
    Electronic Resource
    Electronic Resource
    The barium carbonate procedure for the preparation of glass capillary columns; Further informations and developments (1977)
    Springer
    Chromatographia 10 (1977), S. 181-187 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF02262938
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  • 3
    Electronic Resource
    Electronic Resource
    Practical aspects of the dependence of polarity on temperature (1983)
    Springer
    Chromatographia 17 (1983), S. 481-485 
    Details
    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02263269
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  • 4
    Electronic Resource
    Electronic Resource
    Preparation of apolar glass capillary columns by the barium carbonate procedure (1978)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 149-155 
    Details
    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
    URL: http://dx.doi.org/10.1002/jhrc.1240010306
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  • 5
    Electronic Resource
    Electronic Resource
    Deactivation of glass capillaries by persilylationThe term persilylation denotes complete silylation, in contrast to partial silylation achieved by common procedures.. Part 2: Practical recommendations (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 677-678 
    Details
    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
    URL: http://dx.doi.org/10.1002/jhrc.1240021110
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  • 6
    Electronic Resource
    Electronic Resource
    Deactivation of glass capillary columns by silylation. Part 1: Principles and basic technique (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 31-35 
    Details
    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
    URL: http://dx.doi.org/10.1002/jhrc.1240020110
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  • 7
    Electronic Resource
    Electronic Resource
    Practical capillary gas chromatography - a systematic approachPlenary Lecture to the Thirtieth Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, March 6, 1979. (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 109-117 
    Details
    ISSN: 0935-6304
    Keywords: Gas Chromatography, capillary, glass ; Capillary versus packed column ; Small sample width at inlet important ; Optimized sampling by on-column injection ; Hydrogen as ideal carrier gas ; Efficient and stringent testing of columns needed ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Capillary gc is now rapidly expanding. Naturally, initiation is most often attempted on the basis of the experience acquired with packed columns. However, such an extrapolation is successful only if a number of essential peculiarities of capillary gc are considered. Based on practical examples this paper discusses six essential details: 1) design and maintenance of the gas flow paths, 2) the greatly increased importance of sampling technique, which should not be confined just to stream splitting, 3) the problems in quantitative analysis arising from small sample size, 4) specific sources of trouble related to small amounts of liquid phase, 5) specific arguments for the choice of the carrier gas, clearly pointing to hydrogen as the ideal carrier and, 6) the different way to approach column production. Figures for all selected examples are given.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020303
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  • 8
    Electronic Resource
    Electronic Resource
    Further evidence for the silica layer as produced by acid leaching (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 527-528 
    Details
    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
    URL: http://dx.doi.org/10.1002/jhrc.1240020808
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  • 9
    Electronic Resource
    Electronic Resource
    Capillary columns with immobilized stationary phases. Part 4: A moderately polar phase, OV-1701 (1982)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 13-18 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography, capillary ; Column preparation ; Immobilization of stationary phases ; Procedure for polar phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Whereas the immobilization of apolar silicone phases is essentially understood and mastered, the corresponding treatment of even moderately polar phases remains problematical. Upon attack by peroxide radicals, these phases respond by forming active transformation products rather than by bonding to the support surface or to neighboring molecules. OV-1701 is at present the most polar stationary phase which can reasonably be immobilized. An essential feature of the practical procedure is the prevention of film breakage after coating the inert support surface and before immobilization. Two ways of overcoming this problem are presented.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240050103
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  • 10
    Electronic Resource
    Electronic Resource
    Testing uncoated glass capillaries (1978)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 302-303 
    Details
    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
    URL: http://dx.doi.org/10.1002/jhrc.1240010606
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