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  • 1
    Electronic Resource
    Electronic Resource
    On-line trace enrichment — column liquid chromatography of polar pollutants in surface water using bifunctional membrane-based extraction-disk cartridges (1994)
    Springer
    Chromatographia 39 (1994), S. 239-245 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Membrane-extraction disks ; On-line trace enrichment ; Polar pollutants ; Surface water
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An on-line trace-enrichment system, using a bifunctional membrane extraction-disk cartridge, has been combined with a column liquid chromatography separation for the simultaneous determination of basic, neutral and acidic pollutants in surface water. The enrichment device consisted of a specially constructed holder containing both C-18 and cation-exchange disks. The holder can contain up to 25 disks of 0.5 mm thickness and 4.6 mm diameter. Before trace enrichment of 20 ml of surface water (pH 3.0), calcium ions were removed from the sample by means of an oxalic acid precipitation. Desorption of the cartridge was at elevated temperature using reversed-phase gradient elution; detection was performed with a diode-array UV absorbance detector. The detection limits for the test compounds in surface water are typically 0.5–2 μg/l; the calibration graphs are linear from the lower limit of determination up to 50 μg/l.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02274506
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of polar pollutants in water using an on-line liquid chromatographic preconcentration system (1991)
    Springer
    Chromatographia 32 (1991), S. 445-452 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; On-line preconcentration ; Polar pollutants ; Water (tap and surface)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An isocratic column liquid chromatographic system with UV absorbance detection at 230 nm has been developed for the rapid trace-level determination of a large number of polar pollutants in water. The systems contains two precolumns, in series, which are packed with a styrenedivinylbenzene (PLRP-S) polymer. The second precolumn is also loaded with sodium dodecylsulphate before use. Each precolumn is combined with a PLRP-S analytical column, and aqueous acetonitrile mixtures (pH 3) are used for the separation of neutral as well as acidic and basic pollutants. With 10-ml water samples the detection limits for all analytes, in tap water, are in the low to sub μg/l range. Relevant analytical data are reported and the advantage of using a dodecylsulphate-loaded precolumn over a cation-exchange precolumn is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02327976
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Electrodialytic sample treatment coupled on-line with high-performance liquid chromatography (1990)
    Springer
    Chromatographia 30 (1990), S. 361-366 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrodialytic sample treatment ; On-line coupling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary An electrodialytic sample treatment method coupled on-line with high-performance liquid chromatography (EDIST-HPLC) is discussed in this paper. The performance of EDIST as a function of the donor-phase (sample solution) flow rate, the voltage applied over the electrodialysis block, and the time of dialysis has been studied using the basic drug ephedrine as a model compound. Enrichment of the analyte by a factor of 10–20 was possible. The determination of human plasma spiked with ephedrine is briefly discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02328498
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Theoretical models for electrodialytic sample treatment in trace analysis by liquid chromatography (1994)
    Springer
    Chromatographia 39 (1994), S. 460-468 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Electrodialytic sample treatment ; Computer models ; Analyte enrichment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Basic considerations for analyte enrichment and recovery obtainable by electrodialysis as a sample treatment method are given. Equations are derived which describe the dependence of the concentration profiles of ionic compounds on the electric field strength in a set-up with stagnant donor and acceptor solutions. It is shown that analyte recovery increases when less ion-selective membranes are used in the electrodialysis cell. Computer models are used to estimate the analyte enrichment for a flowing donor (sample) and a stagnant acceptor phase. About 10-fold enrichment can be obtained in an electrodialytic sample treatment system within 20 min under maximum current conditions. A compromise has to be found between analyte recovery and the donor (sample) flow rate.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02278763
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    Paper (German National Licenses)
    Fulltext
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