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  • Capillary GC  (7)
  • Concurrent solvent evaporation  (7)
  • Solvent effects  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Broadening of peaks eluted before the solvent in capillary GC Part 1: The role of solvent trapping (1983)
    Springer
    Chromatographia 17 (1983), S. 357-360 
    Details
    ISSN: 1612-1112
    Keywords: Capillary GC ; Peak deformation ; Solvent trapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary In capillary GC the analysis of solutes eluted before the solvent is often precluded because of severe broadening and distortion of the peaks. This problem has three sources: a) most solutes are partially solvent trapped; b) phase soaking broadens peaks eluted shortly before the solvent and c) slow sample transfer from the injector to the column in splitless injection creates broad initial bands which cannot be re-concentrated to narrow bands. The most important (and troublesome) broadening effect is partial solvent trapping. Full solvent trapping of solutes eluted before the solvent only occurs under special conditions. Most solutes are either partially trapped or non-trapped. Partial solvent trapping is mostly of the weak type, broadening the solute bands less than that due to the evaporation time of the solvent at the column inlet. Deformation of peaks eluted before the solvent by solvent trapping can only be avoided by the selection of conditions which create non-trapping. Rapid introduction of the sample into the column is required, which calls for split or on-column injection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262372
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  • 2
    Electronic Resource
    Electronic Resource
    Broadening of peaks eluted before the solvent in capillary GC Part II: The role of phase soaking (1983)
    Springer
    Chromatographia 17 (1983), S. 361-367 
    Details
    ISSN: 1612-1112
    Keywords: Capillary GC ; Peak deformation ; Phase soaking
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Phase soaking is a solvent effect which tends to reconcentrate peaks eluted after and to broaden peaks eluted before the solvent. The principles of the phase soaking effect on peaks eluted before the solvent are discussed. The broadening effect is distinguished from the broadening effect occurring in the flooded column inlet by partial solvent trapping. It was found that in most cases broadening by partial solvent trapping strongly predominated over broadening by phase soaking. Phase soaking was noticeable only in the neighbourhood of the solvent peak. Phase soaking does not broaden peaks eluted before the solvent as much as it re-concentrates those eluted after it. The two phase soaking effects on the front and the rear of the solvent band (that is, of the soaked zone) differ strongly from each other. Peak broadening by phase soaking is negligible for non-trapped components, because such solutes start their chromatography before a significant quantity of solvent enters the column. Phase soaking only broadens solute bands which were retained by the solvent in the column inlet, that is, bands already broadened by partial solvent trapping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02262373
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  • 3
    Electronic Resource
    Electronic Resource
    Co-injections to avoid peak distortion due to partial solvent trapping in capillary gas chromatography (GC) (1984)
    Springer
    Chromatographia 18 (1984), S. 197-201 
    Details
    ISSN: 1612-1112
    Keywords: Capillary GC ; Co-injection ; Solvent effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Co-injection techniques (introducing additional pure solvent with the sample) were tested to eliminate peak distortion due to partial solvent trapping. Co-injections of solvent identical with the sample solvent were not successful, because first only partial solvent trapping of the strong type could be eliminated and second, there was no practicable method of placing a band of pure solvent ahead of the sample in the column inlet. Successful co-injections have to accept mixing of the sample with the pure solvent. Either the solvent trapping is improved by co-injection of a solvent which enhances solution of the critical solutes in the sample layer, or it creates a phase soaking effect in the stationary phase and reconcentrates broadened bands beyond the flooded inlet. The added solvent must have the appropriate polarity and some of it must remain in the column inlet at least until the sample solvent has completely evaporated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02276732
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  • 4
    Electronic Resource
    Electronic Resource
    Glass wool in the injector insert for quantitative analysis in splitless injection (1984)
    Springer
    Chromatographia 18 (1984), S. 517-519 
    Details
    ISSN: 1612-1112
    Keywords: Capillary GC ; Matrix effect in splitless injection ; Glass wool in injector insert
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The use is suggested of a light packing of (silylated) glass wool in the injector insert between the end of the inserted syringe needle and the column inlet to improve quantitation in splitless injection for samples containing some involatile material. Glass wool reduces the standard deviation of the results but its major advantage is the improvment of the solute transfer onto the column. It reduces or eliminates “matrix effects” in splitless injection where solute transfer, and hence absolute and relative peak areas, depends on the sample composition (a source of serious systematic errors). High injector temperatures are required to overcome the retention of the solutes in the sample byproducts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02267238
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  • 5
    Electronic Resource
    Electronic Resource
    Solvent effects in on-column injection of large sample volumes (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 405-407 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; Solvent effects ; Solvent trapping ; Phase soaking ; Large sample volumes ; 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.1240090708
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  • 6
    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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  • 7
    Electronic Resource
    Electronic Resource
    Determination of wax esters in olive oil by coupled HPLC-HRGC (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 593-594 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; HPLC ; Adulteration of cold pressed olive oil ; 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
    URL: http://dx.doi.org/10.1002/jhrc.1240091011
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  • 8
    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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  • 9
    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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  • 10
    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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