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  • 1
    Electronic Resource
    Electronic Resource
    Determination of gas-liquid partition coefficients by automatic equilibrium headspace-gas chromatography utilizing the phase ratio variation method (1993)
    Springer
    Chromatographia 35 (1993), S. 73-84 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Equilibrium headspace sampling ; Partition coefficient determination ; Theory of chromatography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The new phase ratio variation method is described which represents a convenient way for the determination of gas-liquid partition coefficients for practical purposes, utilizing equilibrium headspace-gas chromatography (EHS-GC). This method is based on the relationship between reciprocal peak area and the phase ratio in the vial containing the sample solution; it involves regression analysis of the EHS-GC measurements of a number of sample vials containing the same sample solution but with a wide variation of phase ratios. Examples are given for both aqueous systems and systems consisting of a stationary (liquid) phase used as the solvent; comparison of the measured values with results obtained by other methods shows satisfactory agreement. A critical discussion of the conditions influencing the accuracy of the analytical results is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278560
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Cryofocusing in the combination of gas chromatography with equilibrium headspace sampling (1986)
    Springer
    Chromatographia 21 (1986), S. 305-311 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace analysis ; Capillary columns ; Trace analysis ; Cryogenic trapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary When headspace gas chromatography utilizing capillary columns is used for trace analysis, sample enrichment is often needed. This involves splitless sample injection of fairly large gas volumes and relatively long sampling times. As a result of this, the band of the sample vapor may be too large causing peak distortion and poor resolution. This problem can be easily overcome by the use of cryogenic trapping. While this can be accomplished by cooling the whole column to subambient temperature during sample introduction, a more convenient way is to utilize part of the first coil of the capillary column as a cryogenic trap. The paper discusses the theoretical background and instrumentation of cryogenic trapping and demonstrates the possibilities through a number of examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311600
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Headspace-gas chromatography: The influence of sample volume on analytical results (1991)
    Springer
    Chromatographia 32 (1991), S. 5-12 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; GC theory ; Influence of sample volume
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The role of the volume of the sample and the sample vial in equilibrium headspace-gas chromatography is discussed. A new term, thesample phase fraction (ΦS) is introduced. It is shown that if the value of ΦS is kept constant, the vial's volume has no influence on the “sensitivity” of the headspace analysis (which is proportional to the concentration of the analyte in the headspace). In a given headspace sampling system, concentration of the compound of interest in the headspace (c G * ) at equilibrium is related to the value of ΦS: a higher ΦS will increase c G * . However, the influence is important only in the case of low distribution coefficients: in the case of higher distribution coefficients this influence is negligible. This conclusion is also true for small changes in the sample volume in duplicate analyses: exact reproducibility of the sample volume is important only in the case of low distribution coefficient values.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262458
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Determination of partition coefficients by automatic equilibrium headspace gas chromatography by vapor phase calibration (1992)
    Springer
    Chromatographia 34 (1992), S. 235-240 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Headspace sampling ; Partition coefficients ; Multiple headspace extraction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Equilibrium headspace gas chromatography has been applied to the determination of the partition coefficients of volatile compounds in water-air systems. Only techniques that are suited to a fully automatic headspace procedure using the pneumatic headspace sampling-technique have been considered. Particularly simple is the technique of “vapor phase calibration —VPC” where an external vapor standard is used to calibrate the concentration of the volatile analyte in the headspace, while the concentration in the sample is found from the difference in the total amount in the vial. This technique is described in detail for 2-butanone in water. Finally, the water-air partition coefficients of several selected volatile compounds at different temperatures are listed together with their temperature functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268351
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Head space gas chromatography with glass capillaries using an automatic electropneumatic dosing system (1979)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 2 (1979), S. 283-287 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Capillary, glass ; Sampling technique ; Semi-automation of head space sampling ; Application to water pollution, coffee aroma, light hydrocarbons in crude oil ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Head space GC using a special electropneumatic sampling system works well in combination with glass capillaries. Because a homogenous gas mixture is already present most problems inherent with inlet splitters are thus avoided. In cases where the high vapor pressure of the sample can cause problems with the pressure controlled sampling system, the use of narrow bore glass capillaries provides the necessary inlet pressure. The use of this powerful and convenient analytical tool for water pollution analysis, flavour analysis and the analysis of volatiles in crude oil samples is shown by examples.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240020606
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    Paper (German National Licenses)
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