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  • 1
    Electronic Resource
    Electronic Resource
    Polarity change in capillary GC by serial-column temperature optimization (SECAT mode in capillary GC) (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 416-422 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; SECAT-technique=stepless fine tuning of capillary selectivity by serial column temperature optimization ; Exponential influence of temperature on selectivity over a wide range found ; SECAT-technique ready for automation of column adjustment on sample composition polarity ; Instrumental and methodological details for primitive self made solution given ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: GC, including capillary GC, is rather inflexible, if a certain column length and stationary phase has been fixed for a given analytical problem. If the sample composition changes, one often has to change the column length and/or stationary phase, at least when something like optimum analytical conditions are needed. Temperature changes (or heating rates) can change the selectivity of a given column only within very limited ranges, due to the exponential effect of temperature on retention time. By serial coupling two chemically different capillaries, each run at another temperature, even the slightest changes of these two temperature values have a dramatic effect on the selectivity of the system for polar substances. We call this technique the SECAT mode of GC. Results are reported as retention index shifts, dependent on SECAT temperature data. This technique can in future easily be automated, thus enabling the analyst, for polar sample analysis, to adjust a given chroma-tographic system to his specific sample composition without touching the instrument.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020709
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A simple high temperature, high pressure safe T-piece for installing micro packed glass columns as well as macrobore capillaries in a GC instrument (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 595-595 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Connection device ; Micro packed columns ; Macrobore capillaries ; 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.1240091012
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Dramatic selectivity changes on carrier gas flow change in a series-coupled GC capillary tandem (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 580-584 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns, in series ; Flow rate changes ; Selectivity ; Retention time ; Residence time ; Multichromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We describe the polarity of selectivity of a GC separation system in terms of Retention Index data. In a series-coupled capillary system having stationary phases of differing polarity even slight (independent!) carrier gas flow changes in one part of the capillary series result in a dramatic change of selectivity. “Dramatic” is a relative term! Using a simple electronically controlled flow changing device we found retention index changes of several hundred units for polar test compounds such as phenols on a SE30/Carbowax tandem. This means: The classical theoretical model for understanding retention (and selectivity) in chromatography must be corrected. We propose a very simple approach involving addition of the expression RESIDENCE TIME to the chromatographic vocabulary. Instead of using flow resistors, one can just add a pressure regulator to the coupling point. A powerful analytical concept is now in easy reach.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240080921
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Native ethylene glycol in wine: Application of a dead volume free, very fast “deans heart-cut” system on-line with multi-chromatography (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 240-243 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary columns, coupled ; Heart cutting ; Multi-chromatography ; Wine analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Data about the existence of native HO—CH2—CH2—OH (MEG) in natural wines and champagne has led to delicate questions because of legal decisions already made to declare wine or champagne illegal for sale if the MEG concentrations found are above 10 mg/liter. Action has been taken because of the DEG (diethylene glycol) disaster in European wines of 1985…86. An incorrect legal decision was made due to the belief that MEG cannot be produced biochemically by grape vines. A further reason may be lack of correct data on native MEG trace concentrations, as a result of the special behavior of this diol. As first member of a homologous series whose higher members (C4) are normally found in all wines at quite high concentration levels, MEG shows extremely adsorptive behavior. The solution of the chromatographic problems is summarized in this paper. MEG concentrations in Riesling as example are in the range of 2 to 6 mg/liter and can easily be increased by biotechnological steps to a level of around 10 to 60 mg/liter. This is again due to the specific adsorptive behavior of MEG, which can be enriched on filter surfaces and displaced when the wine acidity changes with changing types. In order to control and guarantee the qualitative and quantitative results of MEG analyses we used a combination of Deans heart cutting on-line with Multi-Chromatography. It was easy to produce false data by many otherwise useful single column or two-dimensional separation processes, etc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240100506
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    Paper (German National Licenses)
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