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  • 1
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): 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
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020110
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  • 2
    Digitale Medien
    Digitale Medien
    Capiliary columns with immobilized stationary phases. Part 5: Determination of column bleeding; re-silylationPart 4: HRC & CC5 (1982) 13. (1982)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 5 (1982), S. 349-354 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography, capillary ; Persilylated, apolar columns ; Immobilized coatings ; Determination of column bleeding ; Re-silylation of fresh and used columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The bleeding of apolar high temperature columns may well be the critical factor limiting their applicability for GC/MS-coupling, and for high temperature analyses. Therefore, a bleeding determination procedure has been designed as a basis for a systematic approach to the production of low-bleed columns. Re-silylation is a traditional method of reducing column bleeding. Increased efficiency of re-silylation becomes feasible with immoblized coatings. Experience gained so far shows that resilylation of immoblized coatings may indeed result in the expected strongly reduced bleed rates and in improved overall column quality. Re-silylation may also contribute to column washing by enhancing the solubility of adsorbed contaminants.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240050703
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  • 3
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Static coating ; Filling with mechanical closure ; Description of an easy and safe technique ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240050302
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  • 4
    Digitale Medien
    Digitale Medien
    A warning against the use of diluted stock solutions of apolar silicones for coating glass capillary columns (1978)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 1 (1978), S. 221-222 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas Chromatography ; Capillary, glass ; Solution of liquid phase ; Stored solutions produce less thermostable columns ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240010418
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  • 5
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): 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
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020808
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  • 6
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): Gas chromatography, capillary ; Column preparation ; Immobilization of stationary phases ; Procedure for polar phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240050103
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  • 7
    Digitale Medien
    Digitale Medien
    Capillary columns with very thick coatings (1983)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 6 (1983), S. 133-139 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Advantages of very thick coatings ; Separation efficiency correlated with film thickness ; Preparation of columns with very thick coatings ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: It has become common practice with capillary columns to call film thicknesses of 0.1 - 0.3 μm regular or standard, whereas 0.3 - 1.0 μm is considered to denote thick films. Consequently, films with thickness beyond 1μm (we have explored the range up to 8.0 μm) may be termed very thick. Increasing film thickness, at least to about 5 μm, brings important additionl advantages primarily in terms of loading capacity. Columns with very thick coatings may replace the traditional SCOT columns thanks to at least equivalent loading capacity combined with higher separation efficiency, and better stability characteristics. Additional advantages are increased retention, essential for the analysis of very volatile substances, and increased elution temperature, providing a basis for direct water injection.We observe that TZ (the separation number) drops to roughly 50% when the film thickness is increased by a factor of 300 from 0.025 to 8.0 μm, provided TZ is measured with a standard flow of hydrogen. The reduction is only 30% when the thick-film colums are run with individual optimization with nitrogen as a carrier gas. In contrast to standard columns, very thickly coated columns show slightly increased separation efficiency with nitrogen at drastically reduced flow rate. The HETP increases very slightly in the indicated range of flim thickness. This contradicts widespread theoretical expectations, which probably account for the fact that very thick coatings have so far been neglected. Since the preparation of very thick coatings involves some deviations from the standard procedure, complete and detailed instructions are given.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240060304
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  • 8
    Digitale Medien
    Digitale Medien
    Immobilization of vinylated OV-17 and OV-1701 based on combined surface bonding and crosslinking (1983)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 6 (1983), S. 153-155 
    Details
    ISSN: 0935-6304
    Schlagwort(e): Gas chromatography ; Capillary, glass ; Immobilization of moderately polar phases ; Combination of surface bonding and crosslinking ; Vinyl groups in the support surface ; Chemistry ; Analytical Chemistry and Spectroscopy
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240060307
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  • 9
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): 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
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240010306
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  • 10
    Digitale Medien
    Digitale Medien
    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
    Schlagwort(e): 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
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jhrc.1240020303
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