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  • 1
    Electronic Resource
    Electronic Resource
    On-line post-column extraction in column liquid chromatography with electron-capture detection (1986)
    Springer
    Chromatographia 22 (1986), S. 235-240 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Reversed-phase system ; On-line post-column extraction ; Electron-capture detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A post-column extraction module has been used for the on-line coupling of conventional-size (4.6mm i.d.) reversed-phase liquid chromatography (PPLC) and electron-capture detection (ECD). Hexane and toluene were used as extraction solvents, while methanol turned out to be preferable to dioxane and acetonitrile as modifier in the aqueous eluent. In this system the ECD behaves as a concentration-sensitive detector. The band broadening in the evaporation interface, which connects the extraction module with the ECD, dominates the total post-column band broadening; it can be reduced to 3–4 sec by directing at least 0.25–0.30 ml/min (i.e. 25–30%) of the extraction solvent to the ECD. Optimal signal-to-noise ratios were observed if 30–60% of the extraction solvent is directed to the ECD. The noise levels are 5–10 times higher than in systems using a direct coupling of normal-phase LC or narrow-bore reversed-phase liquid chromatography to the ECD. Separations of phenylurea herbicides and chlorophenols demonstrate the applicability of the RPLC-extraction module-ECD system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02268765
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  • 2
    Electronic Resource
    Electronic Resource
    Liquid chromatographic trace enrichment with on-line capillary gas chromatography for the determination of organic pollutants in aqueous samples (1987)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 10 (1987), S. 17-24 
    Details
    ISSN: 0935-6304
    Keywords: Coupled LC-GC ; Retention gap ; LC trace enrichment ; Aqueous samples ; Organic pollutants ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Trace enrichment for the GC analysis of a series of chlorinated pesticides and polychlorinated biphenyls (PCBs) in aqueous samples has been achieved through a simple on-line technique involving sorption on an LC micro-precolumn followed by direct elution into a gas chromatograph with hexane. A 5-m retention gap coupled to the capillary GC column served as the recipient of a relatively large sample volume (ca. 100 μl) introduced into the GC. Partially concurrent solvent evaporation during sample introduction allowed a large sample capacity. Recoveries of more than 95% were observed for the majority of the compounds studied. Using 1.0 ml aqueous samples, detection limits of less than 1 ppt were found. The applicability of the developed method was demonstrated for a river water sample.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240100104
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    On the mechanism of peroxyoxalate chemiluminescence. Quenched chemiluminescence as a detection method in HPLC (1989)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 4 (1989), S. 479-483 
    Details
    ISSN: 0884-3996
    Keywords: Quenched CL ; peroxyoxalate ; mechanism ; detection ; HPLC ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Several analytes such as the inorganic anions bromide, iodide, sulphite and nitrite and organic compounds as substituted anilines and sulphur compounds cause quenching of peroxyoxalate chemiluminescence. A detection method for liquid chromatography based on the quenching phenomenon has been developed. It makes use of an immobilized luminophore, i.e. 3-aminofluoranthene covalently bound via an alkyl-spacer on controlled pore glass, packed in the detector cell.The mechanism behind the quenching has been elucidated by investigating the roles of luminophores (both in the liquid and in solid state) and oxalates in peroxylate CL with respect to quenchers. Most probably the quencher destroys the radical ion pair produced after electron transfer in the last stage of the CIEEL reaction scheme, thus preventing the formation of electronically excited luminophore.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170040163
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