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  • 1
    Electronic Resource
    Electronic Resource
    On-line sample treatment—capillary gas chromatography (1998)
    Springer
    Chromatographia 47 (1998), S. 313-345 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Sample pretreatment ; Coupling on-line to capillary GC ; Robotization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Sample pretreatment is often the bottleneck of a tracelevel analytical procedure. In order to increase performance, increasing attention is therefore being devoted to combining sample pretreatment on-line with the separation technique that has to be used. In the present review, a variety of procedures in use today for sample treatment coupled on-line to capillary gas chromatography (GC) is briefly discussed. Special attention is devoted to coupled-column techniques such as SPE-GC and LC-GC (SPE, solid-phase extraction; LC, column liquid chromatography) which are topics of much current interest, also because of their frequent use in so-called hyphenated systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466538
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of triazine herbicides in surface and drinking waters by off-line combination of liquid chromatography and gas chromatography-mass spectrometry (1992)
    Springer
    Chromatographia 34 (1992), S. 5-13 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Gas chromatography-mass spectrometry ; Water analysis ; Triazine herbicides ; Chemical ionization mass spectrometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Mass spectra of 12 triazines were obtained by electron impact (EI), positive-ion chemical ionization (PCI) and negative-ion chemical ionization (NCI) using methane and isobutane as reagent gases. EI mass spectrometry is more sensitive than PCI and NCI, although the chemical ionization modes increase selectivity markedly. A pre-column packed with polymer stationary phase was employed to preconcentrate surface and drinking water samples. After desorption of the analytes with ethyl acetate, an aliquot was injected directly into the GC-MS system. Atrazine and simizine were found in these samples at 10–80 ppt levels. The limits of detection for both herbicides were below 10 ppt in drinking water.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290451
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Use of membrane extraction disks for on-line trace enrichment of organic compounds from aqueous samples (1990)
    Springer
    Chromatographia 29 (1990), S. 415-418 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Trace enrichment ; Membrane extraction disks ; Triazine herbicides ; 2,3,4-Trichlorophenol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Membrane extraction disks have been recently introduced for the solid-phase extraction of organic compounds from aqueous samples. The material consists of alkyl-modified silica particles enmeshed in an inert PTEE matrix. Aqueous samples containing polar pesticides and herbicides, are preconcentrated on-line from acidic solutions on membrane extraction disks containing immobilized octadecyl-modified silica and analyzed with an isocratic liquid chromatographic system using PLRP-S as the stationary phase and aqueous acetonitrile mixtures (pH 3) as the eluent. Data on the lifetime and the dimensions of the preconcentration disks, and the efficiency and the repeatability of the procedure are reported. For 10 ml samples, the detection limits of the analytes atrazine, simazine and 2,3,4-trichlorophenol in tap water are 0.1–1 ppb.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02261387
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    On-line chromatographic pretreatment of samples with varying salt concentrations for capillary electrophoresis (1997)
    Springer
    Chromatographia 44 (1997), S. 581-588 
    Details
    ISSN: 1612-1112
    Keywords: Capillary electrophoresis ; On-line LC-CE ; Sample pretreatment ; Matrix effects ; Benzoic acids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Various methods are currently under investigation to improve concentration detection limits in capillary electrophoresis (CE). Stacking and isotachophoresis coupled in-line with free-solution electrophoresis are the techniques most frequently used. Samples containing a high and/or varying salt concentration, such as urine and serum, are difficult to handle: usually a significant loss in electrophoretic efficiency is observed compared with samples possessing a low electric conductivity. In the present paper an alternative approach is developed, i.e. a liquid chromatographic (LC)-type of sample pretreatment is coupled on-line with CE. To demonstrate the feasibility of this approach, the separation of three model compounds (benzoates) in water containing up to 400 mM of sodium chloride is studied using a 50 mM borate CE buffer of pH 9.5. The direct injection of samples with high salt concentrations in CE results in peak splitting and/or serious band broadening. These problems are not encountered when using the present LC-CE system. In addition, the detection limits are hardly influenced by the salt concentration of the sample; this underlines the robustness of the system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02466659
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    Paper (German National Licenses)
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