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  • 1
    ISSN: 1612-1112
    Schlagwort(e): Phosphorescence, room-temperature ; Detection, continuous flow ; Liquid chromatography ; Halogenated componds ; Dibenzofurans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary It is shown that sensitized room-temperature phosphorescence in liquid solutions can be successfully applied as a detection method in continuous flow and chromatographic systems. The limits of detection for a series of halogenated naphthalenes and biphenyls obtained by plug injection are roughly the same as those in batch experiments — in the subnanogram region. Liquid chromatograms of mixtures of PCBs, PCNs and polychlorodibenzofurans are given.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    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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  • 3
    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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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Chromatographia 15 (1982), S. 161-166 
    ISSN: 1612-1112
    Schlagwort(e): Reaction detectors ; Liquid chromatography ; Pharmaceutical analysis ; Environmental analysis ; Trace organics analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary Reaction detectors are considerably enhancing the application potential of HPLC particularly when dealing with trace analysis in complex matrices. In principle one distinguishes between segmented and non-segmented reactor system. The theory of band broadening of these designs and some criteria for the choice of the proper type are brieffly discussed. It seems that with a proper construction of the phase separators segmented systems have a wider range of applicability. Applications of reaction detectors in the areas of pharmaceutical and environmental analysis are discussed.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1612-1112
    Schlagwort(e): Chemical excitation source ; Chemiluminescence detector ; Chemical band narrowing ; Dansyl derivative ; Serum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Summary A peroxyoxalate chemiluminescence detection system for liquid chromatography is described. The excitation of fluorophores is generated by the reaction of bis-(2,4,6-trichlorophenyl)oxalate or bis(2,4-dinitrophenyl)oxalate and hydrogen peroxide, which are added to the column effluent. The influence of the solvents and the concentrations of the reagents have been investigated. The influence of the flow cell volume on sensitivity and on band broadening have also been studied and a “chemical band narrowing effect” has been observed. Different types of apparatus have been compared for detection of the emitted light. The system has been used for the detection of the dansyl derivative of a drug with a secondary amine functional group in serum samples. The detection limits are in the 1–10pg range.
    Materialart: Digitale Medien
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