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  • Biochemistry and Biotechnology  (3)
  • Analytical Chemistry and Spectroscopy  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Analysis of C1- and C2-halocarbons in ambient air from remote areas using stainless steel canister sampling, cold trap injection HRGC, and a static calibration technique (1990)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 13 (1990), S. 34-39 
    Details
    ISSN: 0935-6304
    Keywords: Capillary gas chromatography ; Cold trapping ; Sampling in stainless steel canisters ; Calibration ; Halocarbons in remote areas ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5 ml air samples from 1.6 l stainless steel canisters were cryogenically preconcentrated before gas chromatographic separation on a thick-film capillary using a home-made cryotrap. Quantification in the 10-500 ppt range was carried out with an electron capture detector. Problems during the cryotrap step were caused by carrier gas contamination, water and CO2 content of the sample, and a non-optimal heat desorption rate. Their elimination is described in detail. Compound losses by wall adsorption on stainless steel surfaces were observed when dry gases were used for standard generation. A static multipoint calibration technique using humidified He was developed allowing a precise standard generation down to 100 ppt. The concentration changes in the stainless steel canisters could be neglected over a storage period of at least 1 month as long as a sufficient degree of humidity was present. The overall reproducibility of the quantification and calibration technique is in the order of 1-2% for concentrations between 100-400 ppt when daily recalibrations are carried out.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240130108
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Fast and sensitive chemiluminescence determination of H2O2 concentration in stimulated human neutrophils (1995)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 10 (1995), S. 229-237 
    Details
    ISSN: 0884-3996
    Keywords: Polymorphonuclear leukocytes ; hydrogen peroxide ; hypochlorous acid ; respiratory burst ; chemiluminescence ; luminol ; catalase ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: A fast and sensitive chemiluminescence assay for the determination of H2O2 in stimulated neutrophils without the use of enzymes was developed. The method is based on the oxidation of luminol by hypochlorous acid. The chemiluminescence of this reaction is highly dependent on the concentration of hydrogen peroxide.Changes in H2O2 concentration in PMA-stimulated neutrophils were followed by injection of NaOCI to cell suspension at different times after cell stimulation. The short integration time of 2 s permits calculation of actual concentrations of H2O2 without influence of H2O2 decomposition by cellular enzymes or newly produced H2O2 due to dismutation of superoxide anion radicals. Concentrations of H2O2 were diminished by catalase and enhanced by sodium azide owing to inhibition of cellular catalase and myeloperoxidase. Changes in H2O2 concentration upon stimulation could be observed at 3000 cell/mL.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170100406
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Chemiluminescence intensities and spectra of luminol oxidation by sodium hypochlorite in the presence of hydrogen peroxide (1991)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 6 (1991), S. 189-192 
    Details
    ISSN: 0884-3996
    Keywords: Luminol ; sodium hyochlorite ; hydrogen peroxide ; chemiluminescence intensities ; chemiluminescence spectra ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Hydrogen peroxide amplifies the chemiluminescence in the oxidation of luminol by sodium hypochlorite. A linear relationship between concentration of hydrogen peroxide and light intensity was found in the concentration range 5 × 10-8-7.5 × 10-6 mol/l. At 7.5 × 10-6 mol/l H2O2 the chemiluminescence is amplified 550 - fold. The chemiluminescence spectra of these reactions have a wavelength maximum at 431 nm independent of the concentration of hydrogen peroxide. The results indicate that hydrogen peroxide is a necessary component in the chemiluminescent oxidation of the luminol by sodium hypochlorite.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170060309
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanisms of inhibition of chemiluminescence in the oxidation of luminol by sodium hypochlorite (1993)
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 8 (1993), S. 307-313 
    Details
    ISSN: 0884-3996
    Keywords: Luminol ; sodium hypochlorite ; hydrogen peroxide ; inhibition of chemiluminescence ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Two different mechanisms of inhibition of chemiluminescence in the oxidation of luminol by sodium hypochlorite were found. Most substances investigated in these experiments acted by scavenging NaOCI. This mechanism was independent of the concentration of hydrogen peroxide and the incubation time between luminol and inhibitors. The most potent inhibitors were substances containing SH groups. Compounds with amino groups as a target for HOCI/OCI- to yield chloramines were much less effective inhibitors. Another mechanism of inhibition was found for catalase. It depended on the presence of hydrogen peroxide in the incubation medium and the incubation time between luminol and catalase. The enzyme inhibited the luminescence by removing H2O2 at molar concentrations much smaller than those found for all other inhibitors. Our results confirm the present models of the mechanism of generation of luminescence in luminol oxidation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bio.1170080604
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  • 5
    Electronic Resource
    Electronic Resource
    Solvent dependence of the molecular structures of furan and thiophene determined by NMR of partially oriented molecules (1983)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 21 (1983), S. 143-145 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The molecular rα structures of furan and thiophene dissolved in liquid crystals Merck ZLI 1167 and Phase IV were determined from the linear combinations of dipolar H—H and C—H coupling constants derived from the 1H and 1H—13C satellite NMR spectra. Significant variations with the liquid crystal solvent are observed for both molecular structures. The deformations are particularly large in the case of thiophene and, surprisingly, in the normally well behaved ZLI 1167 liquid crystal.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/omr.1270210214
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    Paper (German National Licenses)
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