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  • Artikel: DFG Deutsche Nationallizenzen  (5)
  • Liquid chromatography  (3)
  • Electrodialytic sample treatment  (2)
  • 1
    ISSN: 1612-1112
    Schlagwort(e): Liquid chromatography ; Chlorophenols in water ; Preconcentration ; Post-column photochemical dechlorination ; Electrochemical, UV and fluorescence detection ; Column switching
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A specific HPLC method has been developed for the trace analysis of lower chlorinated aromatic compounds. The method consists of an on-line preconcentration and a post-column reaction step. On-line preconcentration of mono- and dichlorophenols from aqueous samples has been performed using PRP1, a divinylbenzene-styrene copolymeric sorbent as packing material for both pre-and analytical column. Enrichment factors of over 300 were obtained compared to regular (100 μl) loop injections, even for the highly polar monochlorophenols. After reversed-phase separation, post-column photochemical dechlorination is carried out directly in the eluent stream, using a photochemical reactor. Upon dechlorination, fluorescent products are formed, which can be detected selectively. The resulting fluorescence signal shows a linear response to the quantity of solute present over 2 to 3 orders of magnitude (correlation coefficients: 0.990–0.98). For the mono- and dichlorophenols, the detection limit of the photoconversion method is in the lower nanogram range. The method is especially suitable for the analysis of complex matrices such as effluent water samples or biological fluids containing traces of the polar chloroaromatic compounds together with large amounts of other constituents, which interfere when using more general methods of detection like UV absorption. The potential of this technique for automation has been demonstrated by using a microprocessor-controlled column switching unit.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1612-1112
    Schlagwort(e): Liquid chromatography ; Photochemical reaction detection ; Chemical post-column reduction ; Fluorimetric detection ; Air segmented flow systems ; Non-aqueous reversed-phase chromatography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A new photochemical reaction method for the on-line fluorimetric detection of natural vitamin K homologs was developed. In addition to its high sensitivity, the method features an interesting selectivity for the determination of these compounds in a complex matrix such as human serum. The formation of different photolysis products as a function of reaction conditions, and the optimalisation of a segmented flow reaction system will be discussed. The results indicate that the method is 4 times more sensitive than UV detection, and at least as selective as fluorescence detection after post-column chemical reduction.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 16 (1982), S. 237-241 
    ISSN: 1612-1112
    Schlagwort(e): Liquid chromatography ; Electron capture detection ; Improved interface
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary An improved interface for the coupling of a liquid chromatograph (LC) and an electron-capture detector (ECD) allows the use of the LC-ECD combination for the determination of various types of chlorinated aromatic compounds. The addition of up to 6% of dioxan to the hexane used as mobile phase can be tolerated without serious deterioration of detector performance. Derivatization of polar compounds such as anilines, phenylurea herbicides, chlorophenols and hydroxylated polychlorobiphenyls with fluorine-and non-fluorine-containing acid anhydrides is a useful tool to extend the application range of LC-ECD. As an example, the analysis of a spiked soil sample is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Electrodialytic sample treatment ; On-line coupling
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1612-1112
    Schlagwort(e): Column liquid chromatography ; Electrodialytic sample treatment ; Computer models ; Analyte enrichment
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: 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.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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