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  • 1
    Electronic Resource
    Electronic Resource
    High Speed Cryogenic Modulation - A Technology Enabling Comprehensive Multidimensional Gas Chromatography (1999)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 22 (1999), S. 235-238 
    Details
    ISSN: 0935-6304
    Keywords: Cryogenic modulation ; LMCS ; GC×GC ; multidimensional GC ; comprehensive gas chromatography ; petroleum analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: No abstract
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 2
    Electronic Resource
    Electronic Resource
    Studies on cryogenic trapping of solutes during chromatographic elution in capillary gas chromatography (1996)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 403-408 
    Details
    ISSN: 0935-6304
    Keywords: Gas chromatography ; Cryogenic trapping ; Capillary ; Focusing ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cryogenic trapping of solutes leads to narrowing of the chromatographic band. By placing the trap at the end of a capillary column, it is possible to study the effectiveness of the trap in terms of producing a sharpened elution profile. The trap may be heated by supplementary heating, but here convective heating from the GC oven is employed simply by turning off the cryogenic coolant. It is estimated that it takes about 50 s for the trap to heat up sufficiently to allow trapped solute to be remobilized, although this depends upon the oven temperature and thermal mass of the trap. It can also be shown that the more volatile solutes mobilize faster from the trap in this particular mode of operation. The recovery of trapped components shows that there is essentially quantitative trapping, and the solutes are trapped just at the leading edge of the trap.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240190708
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  • 3
    Electronic Resource
    Electronic Resource
    Multidimensional capillary gas chromatography of polychlorinated biphenyl marker compounds (1996)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 19 (1996), S. 622-626 
    Details
    ISSN: 0935-6304
    Keywords: Multidimensional capillary chromatography ; Polychlorinated biphenyls ; PCBs ; Congener ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Multidimensional chromatography was used to resolve the specific chlorobiphenyl (CB) congeners 28, 52, 101, 118, 138, 153, and 180 in technical aroclor standards. Single column analysis of polychlorinated biphenyls (PCBs) results in co-elution of key congeners with other components in the mixture; therefore using two columns of different selectivity was necessary to enhance the resolution achievable on just one column. The HT8 column (8% phenylpolycarborane-siloxane phase) has been reported to have specific selectivity characteristics for improved PCB separation. When coupled with a BPX5 column (5% phenylpolysiloxane-silphenylene phase), it has been shown here to provide unambiguous identification of 7 marker compounds which are used to monitor PCB occurrence and distribution. All seven marker CBs are present in aroclor 1254, and by adjusting the size of the heartcut window, it was possible to obtain resolution of the marker congeners from other congeners. Single column analysis is unable to achieve this result. This offers an alternative to GC-MS analysis.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240191106
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  • 4
    Electronic Resource
    Electronic Resource
    Comprehensive Two-Dimensional Gas Chromatography Using a Modulating Cryogenic Trap (1998)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 620-622 
    Details
    ISSN: 0935-6304
    Keywords: Multidimensional gas chromatography ; comprehensive two-dimensional gas chromatography ; kerosene analysis ; cryogenic modulation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Design and Implementation of Comprehensive Gas Chromatography with Cryogenic Modulation (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 245-252 
    Details
    ISSN: 0935-6304
    Keywords: LMCS ; cryogenic modulation ; comprehensive gas chromatography ; GC×GC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Comprehensive gas chromatography is the realization of true continuous multidimensional (dual column) gas chromatography. The key requirement in the comprehensive GC experiment is that the second dimension analysis is completed in a rapid time-frame compared to the elution of components in the first dimension, and that the two coupled dimensions represent ‘orthogonal’ analyses towards the analytes to be separated. The former normally necessitates pulsing of contiguous segments of each chromatographic band from the first to the second dimensions. The two dimensions should be in fluid communication. The comprehensive GC×GC experiment passes all the column flow from the first column to the second column, leading to no sample loss, but this also requires a suitable method for time- or zone-compression of the band to be pulsed to the second column. The final pulse should be narrow, and should be delivered to the second column quickly. A simple procedure can achieve this using the cryogenic modulator that has been recently described by this group. The system uses a cryogenic trap which can be moved away from the cooled zone of the column faster than 10 ms. A fast-acting pneumatic ram achieves this performance. The cooled column heats up to the prevailing oven temperature within 10-15 ms. Molecules as volatile as C5 alkanes or small aromatics will be fully retained by the trap within the period of modulation used for GC×GC. The technique is simple to implement and requires no special column connections. Using a gas chromatograph which allows control of external events and can acquire from a detector at 50 Hz or faster, and a timing controller for modulation, the comprehensive result can easily and effectively be achieved.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Enhancement of Signal-to-Noise Ratios in Capillary Gas Chromatography by Using a Longitudinally Modulated Cryogenic System (1998)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 21 (1998), S. 32-38 
    Details
    ISSN: 0935-6304
    Keywords: LMCS ; column bleed ; modulation ; signal enhancement ; capillary GC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---A Longitudinally Modulated Cryogenic System (LMCS) was evaluated for its use in detection enhancement in capillary gas chromatography. The mechanism for chromatographic re-elution for the LMCS is substantially different to other cryogenic devices. The cooled region of the capillary column in which chromatographic bands may be focused is heated by the surrounding oven temperature either by moving the trap along the column, or by moving the column out of the trap. By continually modulating the LMCS at the detector end of the capillary column, signal-to-noise ratios of routine chromatograms can be readily increased by a factor of ten, thus enhancing chromatographic detection. Base widths of peaks, which are often about 2-3 s or more can be easily reduced to 0.3 s when the LMCS is employed in the detection enhancement mode, thus offering a simple avenue to improved peak height sensitivity in capillary gas chromatography.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Comparison of Thermal Sweeper and Cryogenic Modulator Technology for Comprehensive Gas Chromatography (2000)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 23 (2000), S. 253-258 
    Details
    ISSN: 0935-6304
    Keywords: Comprehensive gas chromatography ; cryogenic modulation ; semi-volatile aromatics ; thermal sweeper ; peak widths ; peak asymmetries ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---The two current technologies for achieving comprehensive gas chromatography (GC×GC) - the thermal sweeper and the cryogenic modulator - are compared in an interlaboratory study using a multicomponent semi-volatile aromatic compound sample. The same column set (phases, film thickness, dimensions of columns) and conditions of oven temperature program were used. Carrier gas flow settings however were different for the data reported here. The thermal sweeper has a longer overall length due to the extra ca. 30 cm length of narrow bore tubing used for the modulator/accumulator section. Data reveal that the two methods behave in an analogous manner in respect of delivering GC×GC results, with key peak parameters of peak widths and symmetry measures showing good correlation. Retention time dissimilarity on the first dimension columns in the two systems arises from different flow rates used, however the second column retention is similar, and this is due to the resulting different elution temperatures that peaks elute on the first dimension in each system. Overall, the two approaches to GC×GC appear to produce equivalent results within the scope of the application studied. Each system does have its experimental limitations; the thermal sweeper has what may be called a ‘thick film effect’, where at high temperature it can be difficult to sufficiently trap the migrating bands in the accumulator column, and the pulsing of solutes in the cryogenic system may suffer from a ‘thick wall effect’ if a column with too thick a wall dimension is used at low oven temperature.
    Additional Material: 4 Ill.
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  • 8
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    New operational modes for multidimensional and comprehensive gas chromatography by using cryogenic modulation (2000)
    Elsevier
    Details
    Publication Date: 2000-01-01
    Print ISSN: 0021-9673
    Electronic ISSN: 1873-3778
    Topics: Chemistry and Pharmacology
    Published by Elsevier
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  • 9
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    Time-resolved cryogenic modulation for targeted multidimensional capillary gas chromatography analysis (2000)
    Elsevier
    Details
    Publication Date: 2000-09-01
    Print ISSN: 0021-9673
    Electronic ISSN: 1873-3778
    Topics: Chemistry and Pharmacology
    Published by Elsevier
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  • 10
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    Longitudinally Modulated Cryogenic System. A Generally Applicable Approach to Solute Trapping and Mobilization in Gas Chromatography (1997)
    American Chemical Society
    Details
    Publication Date: 1997-07-01
    Print ISSN: 0003-2700
    Electronic ISSN: 1520-6882
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society
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