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  • 1
    Electronic Resource
    Electronic Resource
    Minimum column temperature required for concurrent solvent evaporation in coupled HPLC-GC (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 435-440 
    Details
    ISSN: 0935-6304
    Keywords: On-line coupled HPLC-GC ; Concurrent solvent evaporation ; Loop-type Interface ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concurrent solvent evaporation using the loop-type HPLC-GC interface requires that the GC oven temperature be above the eluent boiling point at the given carrier gas inlet pressure in order to prevent eluent flowing into the GC capillary column. Corresponding oven temperatures representing minimum oven temperatures for eluent transfer were experimentally determined for solvents and solvent mixtures of interest for use as HPLC eluents. Evaluation of eluents for concurrent evaporation is discussed. Recommended lengths of uncoated column inlets (pre-columns) are derived from the mechanisms involved in solvent evaporation. Temperatures listed as minimum column temperatures for concurrently evaporating HPLC eluents are also useful for estimating maximum applicable column temperatures when working with the conventional retention gap or partially concurrent solvent evaporation techniques in coupled HPLC-GC.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240100803
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  • 2
    Electronic Resource
    Electronic Resource
    Loop-type interface for concurrent solvent evaporation in coupled HPLC-GC. Analysis of raspberry ketone in a raspberry sauce as an example (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 518-523 
    Details
    ISSN: 0935-6304
    Keywords: Coupled HPLC-GC ; Concurrent solvent evaporation ; Loop-type interface ; Raspberry ketone ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Presently, two coupling techniques are used for directly introducing HPLC fractions into capillary GC: The retention gap technique (involving negligible or partially concurrent solvent evaporation) and fully concurrent solvent evaporation. While the former involves use of a conventional on-column injector, it is now proposed that concurrent solvent evaporation technique be carried out using a switching valve with a built-in sample loop. The technique is based on the concept that the carrier gas pushes the HPLC eluent into the GC capillary against its own vapor pressure, generated by a column temperature slightly exceeding the solvent boiling point at the carrier gas inlet pressure. Further improvement of the technique is achieved by flow regulation of the carrier gas (accelerated solvent evaporation) and backflushing of the sample valve (improved solvent peak shape).Concurrent solvent evaporation using the loop-type interface is easy to handle, allows transfer of very large volumes of HPLC eluent (exceeding 1 ml), and renders solvent evaporation very efficient, allowing discharge of the vapors of 1 ml of solvent through the column within 5-10 min.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240090906
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  • 3
    Electronic Resource
    Electronic Resource
    Co-solvent effects for preventing broadening or loss of early eluted peaks when using concurrent solvent evaporation in capillary GC. Part 1: Concept of the technique (1988)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 11 (1988), S. 388-394 
    Details
    ISSN: 0935-6304
    Keywords: Solvent effects ; Co-solvent effects ; Concurrent solvent evaporation ; Large sample volumes ; Coupled HPLC-GC ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The concept and some first results of a method are described for evaporating large volumes of solvent in a relatively short pre-column (retention gap) in such a way that solvent trapping retains volatile components in the inlet up to completion of solvent evaporation. The method was developed for transferring large volumes (easily exceeding 1 ml) of HPLC eluent to GC when using on-line coupled HPLC-GC, but is equally suited for injecting large sample volumes (at least some 50 μl) and could be particularly useful for introducing aqueous solutions.Concurrent solvent evaporation allows introduction of very large volumes of liquid into GC. However, peaks eluted up to some 40-80° above the column temperature during introduction of the liquid are strongly broadened due to the absence of solvent trapping. On the other hand, previous retention gap techniques involving solvent trapping were not suited for transferring very large volumes of liquid into GC. Using a relatively high boiling co-solvent added to the sample or the HPLC eluent, advantages of concurrent solvent evaporation can be combined with solute reconcentration by solvent effects, allowing elution of sharp peaks starting at the column temperature during introduction of the sample.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240110506
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  • 4
    Electronic Resource
    Electronic Resource
    Coupled HPLC-capillary GC - state of the art and outlook (1985)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 8 (1985), S. 726-733 
    Details
    ISSN: 0935-6304
    Keywords: Coupled HPLC-capillary GC ; Retention gap ; Concurrent solvent evaporation ; Extraction techniques ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: HPLC fractions involving eluents of low to intermediate polarity can be introduced into capillary GC using the retention gap technique. Partial or complete solvent evaporation during sample introduction reduces the length of, or almost eliminates, the zone in the column inlet (retention gap) flooded by the introduced liquid, allowing introduction of larger HPLC fractions and/or use of shorter retention gaps. The corresponding techniques are reviewed. The retention gap technique is poorly suited for water-containing HPLC eluents (reversed phase HPLC) and fails completely if HPLC eluents contain, e.g., buffer salts. Various techniques for extracting such HPLC eluents are considered, preference being given to extraction into GC stationary phases from where solutes are thermally desorbed into the GC separation column. Limiting factors are diffusion of solutes within the liquid phase to be extracted and retention power of the extraction tubes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240081107
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  • 5
    Electronic Resource
    Electronic Resource
    Concurrent solvent evaporation for on-line coupled HPLC-HRGC (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 95-101 
    Details
    ISSN: 0935-6304
    Keywords: Coupled HPLC-capillary GC ; Concurrent solvent evaporation ; Retention gap ; Solvent effects ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A technique is proposed which allows introduction of very large volumes of liquid (10 ml were tested) into capillary columns equipped with short (1-2 m long) retention gaps. It is based on concurrent solvent evaporation, i.e. evaporation of the solvent during introduction of the sample. The technique presupposes high carrier gas flow rates (at least during sample introduction) and column temperatures near the solvent boiling point. The major limitation of the method is the occurrence of peak broadening for solutes eluted up to 30°, in some cases up to 100°, above the injection temperature. This is due to the absence of solvent trapping and a reduced efficiency of phase soaking. Therefore, use of volatile solvents is often advantageous. Application of the concurrent solvent evaporation technique allows introduction of liquids which do not wet the retention gap surface. However, the method is still not very attractive for analysis of aqueous or water-containing solutions (reversed phase HPLC).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240090208
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  • 6
    Electronic Resource
    Electronic Resource
    Column temperature during eluent transfer with concurrent eluent evaporation in coupled HPLC-HRGC (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 297-301 
    Details
    ISSN: 0935-6304
    Keywords: Coupled HPLC-HRGC ; Concurrent solvent evaporation ; Column temperature during eluent introduction ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Concurrent solvent evaporation is suited for coupled HPLC-HRGC if solutes elute at intermediate to high column temperatures - otherwise retention gap techniques are more appropriate. Concurrent eluent evaporation using a loop-type interface requires that the GC oven temperature during eluent introduction be above the eluent boiling point at the carrier gas inlet pressure applied. An experimental background is given for facilitating selection of the appropriate column temperature.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240100515
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  • 7
    Electronic Resource
    Electronic Resource
    Coupled HPLC-GC for determining PCBs in fish (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 416-417 
    Details
    ISSN: 0935-6304
    Keywords: Coupled HPLC-GC ; Loop-type interface ; Concurrent solvent evaporation ; PCBs in fish ; 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.1240100713
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