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  • Gas chromatography  (21)
  • Gas Chromatography  (9)
  • Solvent effects  (4)
  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Splitless injection and the solvent effect (1978)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 57-64 
    Details
    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
    URL: http://dx.doi.org/10.1002/jhrc.1240010112
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  • 3
    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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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    Co-injections to avoid peak distortion due to partial solvent trapping in capillary gas chromatography (GC) (1984)
    Springer
    Chromatographia 18 (1984), S. 197-201 
    Details
    ISSN: 1612-1112
    Keywords: Capillary GC ; Co-injection ; Solvent effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Co-injection techniques (introducing additional pure solvent with the sample) were tested to eliminate peak distortion due to partial solvent trapping. Co-injections of solvent identical with the sample solvent were not successful, because first only partial solvent trapping of the strong type could be eliminated and second, there was no practicable method of placing a band of pure solvent ahead of the sample in the column inlet. Successful co-injections have to accept mixing of the sample with the pure solvent. Either the solvent trapping is improved by co-injection of a solvent which enhances solution of the critical solutes in the sample layer, or it creates a phase soaking effect in the stationary phase and reconcentrates broadened bands beyond the flooded inlet. The added solvent must have the appropriate polarity and some of it must remain in the column inlet at least until the sample solvent has completely evaporated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276732
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  • 6
    Electronic Resource
    Electronic Resource
    A current, easily reparable form of damage to GC capillaries (1978)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 307-308 
    Details
    ISSN: 0935-6304
    Keywords: Gas Chromatography ; capillary, glass, diagnosis of damage ; repair by partial washing ; partial reimpregnation/deactivation ; repair test ; 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.1240010609
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  • 7
    Electronic Resource
    Electronic Resource
    Static coating: Filling the column by pressure (1980)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 525-526 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Static coating ; Filling the column by pressure, not by vacuum ; Device for filling by pressure ; 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.1240031009
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  • 8
    Electronic Resource
    Electronic Resource
    Evaluation of syringe handling techniques for injections into vaporizing GC injectors (1980)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 627-633 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Vaporizing injectors ; Dicrimination of high-boiling components ; Elution out of the syringe needle ; “Hot needle”, “solvent flush” techniques ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Unequal elution of sample components of different volatility out of the syringe needle is one of the major causes for discrimination occuring during the injection, i.e. the phenomena which results in peak areas for the high boiling compounds which are too small compared with the volatiles. This problem, associated with all vaporizing injectors that are used with syringes, can be minimized by careful choice of the needle handling technique. Various methods are compared experimentally. The “solvent flush” method is discussed in detail and demonstrated to be ineffective for reducing losses in the syringe needle. The “hot needle” technique, where the empty needle is preheated in the injector before pushing the plunger, was found to be superior or equal to an improved “solvent flush” method (which included preheating the needle and omitting the air plug between sample and flushing solvent. Generally it was found that the discrimination due to the syringe needle was reduced for larger sample volumes, although no further changes were noticed when these exceeded 2.5 to 3μl.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240031205
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  • 9
    Electronic Resource
    Electronic Resource
    Static coating: An attempt to optimize a straightforward technique involving mechanical closure of the column (1982)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 119-123 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Static coating ; Filling with mechanical closure ; Description of an easy and safe technique ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The static technique is commonly accepted as the most universal and scientific method of coating. At the same time, however, it is said to be experimentally demanding. Great efforts have therefore been made to render the method easier and safer, resulting in a wealth of recommendations confusing non-experts. Over a period of two years we have practically applied most of the reported procedures with the aim of studying their practical convenience. We do not doubt that most procedures are comparably suitable in the hands of expert users, i. e. once the initiation efforts have been forgotten, or are otherwise of little interest. We have attempted to describe a method which is specifically suited for easy and quick introduction to beginners. The method is based on mechanical column closure. The principles of the method are discussed, and a comprehensive description of its practical application is given.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240050302
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  • 10
    Electronic Resource
    Electronic Resource
    Trace analysis of halocarbons in water; Direct aqueous injection with electron capture detection (1983)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 6 (1983), S. 11-15 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; ECD ; Halocarbons in water, 0.1-10 ppb ; 0.5-2 μl injected on-column ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interest in monitoring halogenated organics in drinking water and natural surface and ground water in the low ppb range continues to grow. There is a tendency to include still more volatile halocarbons, the trace determination of which is known to be rather demanding. This prompted us to re-examine the feasibility of large-volume direct aqueous injection onto capillary columns, coupled with ECD. A primary problem was to avoid simultaneous elution of water with halocarbons, since water suppresses the ground current of the ECD. The following measures contributed to the solution of this problem.Apolar, extremely inert, columns are required to elute water completely, and even before very light halocarbons. Their coatings have to be far thicker (≍ 5 mUm) than commonly employed thick films since they must permit isothermal analysis at a column temperature around 100°C in order to ensure rapid and complete elution of water. Finally, it is essential that sampling be carried out on-column for two reasons: diffusion of water vapor in the injector, resulting in delayed elution, is then eliminated, and peak distortion during splitless injection is avoided.Although we now know that persilylated columns with immobilized coatings withstand routine water injections, more longterm experience is needed to provide detailed recommendations for the handling of these columns.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240060103
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