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  • 11
    Electronic Resource
    Electronic Resource
    Characterization of chemically bonded phases on precoated thin-layer plates by29Si and13C cross-polarization and magig-angle spinning NMR (1986)
    Springer
    Chromatographia 21 (1986), S. 687-692 
    Details
    ISSN: 1612-1112
    Keywords: Thin layer chromatography ; Chemically bonded phases ; Examination by29Si and13C NMR
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The paper reports results for commercial precoated plates and home-made bonded phases for TLC examined by29Si and13C NMR of solid samples. The NMR spectra readily reveal differences in degree of silylation, details pertaining to the type of reactive silanes used, and differences in the methods of synthesis. They can also be used to explain the cause of the wettability problems encountered with some types of (precoated) TLC plates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02313680
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    Paper (German National Licenses)
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  • 12
    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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    Paper (German National Licenses)
    Fulltext
  • 13
    Electronic Resource
    Electronic Resource
    Derivatization of carboxylic acids with 9-bromomethylacridine using micellar phase-transfer catalysis (1989)
    Springer
    Chromatographia 28 (1989), S. 267-273 
    Details
    ISSN: 1612-1112
    Keywords: Micellar phase-transfer catalysis (MPTC) ; Pre-column derivatization carboxylic acids ; 9-Bromomethylacridine ; Fluorescence detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Micellar phase-transfer catalysis (MPTC) offers the opportunity to derivatize carboxylic acids directly in an aqueous matrix without prior extraction of the acids into a suitable aprotic solvent. The currently developed MPTC system consists of a non-ionic surfactant, Arkopal N-130, an ion-pair agent, tetrakis-(decyl)-ammonium bromide, and a novel fluorescence reagent, 9-bromomethylacridine. The MPTC system can be applied to the derivatization of many types of carboxylic acids. The reaction rate is affected by the lipophilicity of the acid and by the presence of other functional groups. For lipophilic carboxylic acids the reaction is complete within 5 min at 60°C and pH 7.0.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260773
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    Paper (German National Licenses)
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