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  • 1
    Electronic Resource
    Electronic Resource
    Sensitized room-temperature phosphorescence for detection in continuous flow and chromatographic systems (1982)
    Springer
    Chromatographia 15 (1982), S. 218-222 
    Details
    ISSN: 1612-1112
    Keywords: Phosphorescence, room-temperature ; Detection, continuous flow ; Liquid chromatography ; Halogenated componds ; Dibenzofurans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02265650
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  • 2
    Electronic Resource
    Electronic Resource
    Oxalate ester addition from a solid reagent bed for chemiluminescence detection in HPLC (1986)
    Springer
    Chromatographia 21 (1986), S. 587-595 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid Chromatography ; Chemiluminescence detection ; Solid reagent bed ; Quinone detection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The combination of solid-state peroxyoxalate chemiluminescence detection and post-column chemical reaction systems in liquid chromatography is investigated. Bis-2,4,6-trichlorophenyloxalate (TCPO) is added from a solid reagent bed with the fluorophore, 3-aminofluoranthene, immobilized on glass beads. Hydrogen peroxide generated photochemically by quinone analytes is measured. Flow splitting is shown to be a simple means of reagent addition with a negligible band broadening effect. This system is compared to a more flexible dualpump design. To minimize band broadening in both systems, the reagent bed is located out of the path of the chromatographic effluent. Detection limits are in the sub-picomole range, an imporvement relative to those previously reported with TCPO added in the liquid phase. These systems can be easily be adapted for detection of peroxide generated by other post-column reactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311841
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  • 3
    Electronic Resource
    Electronic Resource
    Low-level interferences in peroxyoxalate chemiluminescence (1990)
    New York, NY : Wiley-Blackwell
    Biomedical Chromatography 4 (1990), S. 92-95 
    Details
    ISSN: 0269-3879
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine
    Notes: The role of interferences at concentrations lower than 10-3 M in peroxyoxalate chemiluminescence is examined based on experimental results available in the literature. Implications for fluorophore and for hydrogen peroxide determinations are discussed. An interpretation in terms of the reaction mechanism is proposed.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bmc.1130040303
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  • 4
    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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  • 5
    Electronic Resource
    Electronic Resource
    The proton exchange reaction between indene and the indenyl anion (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 574-576 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton exchange reaction between the indenyl carbanion and its parent compound indene has been studied by NMR as a function of temperature. The rate of this bimolecular reaction is very low and has been found to be strongly dependent on the polarity of the solvent. In solvents like dimethoxyethane (∊ = 7·2) and diglyme the reaction becomes manifest in the NMR spectrum only at elevated temperatures (T 〉 150°C). In hexamethylphosphortriamide (∊ = 30) the rate is much greater and line broadening may be observable at room temperature. The reaction in this solvent is characterised by a frequency factor f = 7 × 107 1 mol-1 s-1, an activation enthalpy ΔH ≠ = 9·5 kcal mol-1 and an entropy of activation ΔS≠ = -23 e.u. The low reaction rate and its solvent dependence are briefly discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270061104
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  • 6
    Electronic Resource
    Electronic Resource
    The NMR spectra of the carbanions of xanthene and thioxanthene. Evidence for paratropism (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 245-249 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton NMR spectra of the carbanions of xanthene [XH]- and thioxanthene [TxH]- have been recorded and interpreted. Paratropism in the central rings of [XH]- and [TxH]- is inferred from a comparison of the chemical shifts with those of the carbanion of 9,10-dihydroanthracene [AH]-. The contributions to the chemical shifts arising from n-electron excess charges, local dipoles and magnetic anisotropies are discussed. Numerical values for the various ring currents have been estimated by a least squares analysis of the observed chemical shifts after applying corrections for the excess charge effect. The results point to a strongly increasing paramagnetic ring current in the central ring in the order [AH]-, [TxH]-, [XH]-.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060413
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  • 7
    Electronic Resource
    Electronic Resource
    Interpretation of the asymmetrical ESR hyperfine spectrum of sodium pyrazine [Na P] in DME in the low temperature region. Evidence for the triple ion [Na P Na]+ (1974)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 6 (1974), S. 448-451 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ESR spectrum of Na pyrazine in DME, at temperatures below -50°C, has been studied in detail. It is shown that two paramagnetic species with slightly different g values are present in the solution, i.e. the sodium pyrazine ion pair [Na P] and the iriple ion [Na P Na]+. The interpretation is based on the concentration dependence of the spectrum.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270060811
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  • 8
    Electronic Resource
    Electronic Resource
    The alkali cation effect on the 1H NMR chemical shifts of the indenyl carbanion (1979)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 12 (1979), S. 684-686 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The complex character of the temperature dependence of the 1H NMR chemical shifts of indenyl-lithium and -sodium in dimethoxyethane is explained. It is shown that the cation causes a polarisation of the C—H bonds and thus influences the proton shifts of the anion, both directly by its electric field along the bonds (the direct effect) and indirectly via its effect on the π-electron distribution (the indirect effect). The indirect effect is inferred from 13C NMR chemical shift data. By subtracting the temperature dependent contribution of the indirect effect from the experimental 1H data, the direct effect is visualised. It appears that information on ion paris obtained by 1H and 13C NMR on the one hand and optical spectroscopy on the other hand is complementary. Apparently, aggregation of ion pairs does not seriously affect the chemical shift data.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270121207
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