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  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 16 (1993), S. 459-463 
    ISSN: 0935-6304
    Keywords: LC-GC ; Aqueous samples ; Large volume injection ; PTV injector ; Solid-phase extraction ; Thermal desorption ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A system is described that allows the introduction of large volumes of water samples in capillary GC. Water elimination is carried out in the solvent split mode in a PTV injector with a packed liner. Two ways of separating water and analytes, i.e. evaporative and non-evaporative (solid-phase extraction), are compared. Sampling in the solid-phase extraction mode is favorable both in terms of recovery as well as with regard to sampling time. Quantitative recovery is obtained for priority pollutants ranging in volatility from dimethyl-phenol to phenanthrene. Losses occur for more volatile compounds, but even for these compounds the repeatability of the recoveries remains acceptable. With the system described here, water samples up to at least 1 ml of water can be directly analyzed. The detection limits are in the sub-ppb range.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Microcolumn Separations 5 (1993), S. 429-432 
    ISSN: 1040-7685
    Keywords: large volume injections ; PTV injector ; electron capture detection ; multidimensional gas chromatography ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In this paper, a system is presented that allows direct introduction of large volumes of methylene chloride in capillary gas chromatography (GC) using the electron capture detector (ECD). The system is based on a two-dimensional (one-oven) GC instrument equipped with a programmed temperature injector. During sample introduction, the solvent is eliminated via the split line. Residual traces of methylene chloride that enter the precolumn are eliminated via a column-switching device located between the precolumn and the analytical column. The system is used for the analysis of pesticides and polychlorinated biphenyls (PCBs) in methylene chloride at ultra low concentrations. The introduction of large sample volumes significantly improved the detection limits. Using the system described here, the solvent exchange step, normally necessary when the ECD is used to analyze samples containing methylene chloride as the solvent, is no longer required.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1040-7685
    Keywords: programmed-temperature sample introduction ; PTV injector ; large volume injection ; on-line LC-GC interfacing ; water analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The introduction of large sample volumes in capillary gas chromatography is becoming increasingly important in various application areas. Especially in the analysis of very dilute sample (e.g., environmental samples) and in coupled LC-GC, large volume sampling is extremely important. Programmed-temperature sample introduction is shown to be an attractive technique for these purposes.In this paper we present some applications of large volume sampling in environmental analysis. Water samples were analyzed using both off-line and on-line extraction with gas chromatography (GC) analysis. In the off-line method, pollutants were extracted into hexane or methylene chloride. Using the programmed-temperature injector, up to 250 μL of the extract could be introduced into the GC system. In this way, reproducible quantitative analysis of PAHs and herbicides were achieved at sub-ppb concentrations using flame ionization detection. In the on-line mode, pollutants were preconcentrated on a short liquid chromatography (LC) column packed with a PLRP-S solid phase extraction material. After the trapping step, the components were desorbed by ethyl acetate and transferred directly into the programmed-temperature vaporizer (PTV-GC) system. Using this method, detection limits below about 1 ppb of herbicides in water were obtained.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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