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  • 1985-1989  (8)
  • 1955-1959
  • Gas chromatography  (5)
  • Phenolics  (2)
  • 13C Relaxation Times  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Fine root production of astringent phenolics (1989)
    Springer
    Oecologia 79 (1989), S. 563-565 
    Details
    ISSN: 1432-1939
    Keywords: Phenolics ; Fine roots ; Stress gradient ; Vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Chemical quality of fine roots (〈1 mm diameter) was determined over a gradient of species composition in the Mixed Mesophytic Forest Region. Ash-free nitrogen, calcium, and phosphorus concentrations of roots declined by 49, 41, and 72%, respectively, over a gradient of increasing soil acidity (pH 5.3 to 4.7). Lignin concentration was unrelated to either the vegetation gradient or any of the soil changes it encompassed; however, astringent phenolics increased by 275% over the same gradient. Trends in the chemical constituency of fine roots suggest that the production of phenolics in below-ground plant parts is increased on nutrient-poor sites. This response is best related to changes in species composition, especially increasing importancy of Quercus spp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00378676
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Intraspecific variation in production of astringent phenolics over a vegetation-resource availability gradient (1987)
    Springer
    Oecologia 72 (1987), S. 211-215 
    Details
    ISSN: 1432-1939
    Keywords: Phenolics ; Stress gradient ; Vegetation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The chemical constituency of flowering dogwood (Cornus florida L.) and red maple (Acer rubrum L.) foliage was analyzed over a species compositional gradient to test the hypothesis that over subtle gradients of moisture and nutrient availability production of phenolic compounds will be increased on sites of greatest stress. Calcium and nitrogen concentrations declined along the gradient in both species, while phosphorus showed a significant decline only in red maple. Lignin concentrations in both species were unrelated to the vegetation gradient, but astringent phenolics increased by 156% and 159% in dogwood and red maple, respectively. The correlation between production of polyphenolds and site quality supports previous observations that under conditions of environmental stress production of many secondary compounds is increased, and suggests that this relationship is significant over subtle environmental gradients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379270
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Sampling and analysis of airborne methylbromide (1989)
    Springer
    Chromatographia 27 (1989), S. 37-43 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Methylbromide ; Charcoal tubes ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Air sampling of methylbromide using 900 mg HBr-treated activated charcoal tubes, followed by solvent desorption and FID or ECD chromatographic analysis, makes it possible to evaluate concentrations ranging from 0.2 ppm (1 mg×m−3) to 250 ppm (1g×m−3) at ambient temperature even with a high hygrometric level. Thermal desorption does not lead to satisfactory results.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02290402
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Ethylene oxide pollution evaluation part I: Sampling with active charcoal tubes (1986)
    Springer
    Chromatographia 21 (1986), S. 201-204 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Ethylene oxide ; Active charcoal tubes ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Air sampling of ethylene oxide on active charcoal tubes followed by GC analysis is a frequently proposed method. This paper studies just to what extent it can be used, defining its limitations (concentration range, influence of ambient temperature and relative humidity), which are seldom taken seriously into account. This method proves inadequate to determine low pollution levels, i.e. around 2 mg m−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311887
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Sampling and analysis of airborne chlorinated methanes — Comparison of FID and ECD (1989)
    Springer
    Chromatographia 28 (1989), S. 617-619 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Chlorinated methanes ; Activated charcoal sampling ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A sampling method using activated charcoal, followed by percolation with ethanol and FID or ECD chromatographic analysis, depending on the concentrations to be monitored, makes it possible to evaluate concentrations of methylene chloride between 5 and 1000mg m−3, chloroform between 0.1 and 2000mg m−3, and carbon tetrachloride between 0.015 and 1000mg m−3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260689
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  • 6
    Electronic Resource
    Electronic Resource
    Ethylene oxide pollution evaluation Part II: Sampling on HBr-treated charcoal tubes (1986)
    Springer
    Chromatographia 21 (1986), S. 269-273 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Ethylene oxide ; HBr-treated charcoal tubes ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Air sampling of ethylene oxide on HBr-treated charcoal tubes followed by capillary GC analysis of the 2-bromoethanol produced allows pollution control evaluation for concentrations ranging from 0.2 to 20 mgm−3. The adequacy of the method is assessed taking into account ambient temperature and relative humidity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02311880
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Air-sampling of three tertiary amines (triethylamine, dimethylisopropylamine, dimethylethylamine) (1985)
    Springer
    Chromatographia 20 (1985), S. 5-8 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; H2SO4-coated silica gel ; Air pollution (foundries) ; Tertiary amines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary After a brief review of the main publications dealing with air-sampling and analysis of aliphatic amines, the authors propose and investigate two sampling methods (bubbling through a sulfuric acid solution, trapping on sulfuric acid-treated silica-gel) for three tertiary aliphatic amines commonly encountered in foundries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02260478
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Investigation of prototropic equilibria by carbon-13 relaxation time analysis (1987)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 25 (1987), S. 16-20 
    Details
    ISSN: 0749-1581
    Keywords: 13C NMR ; 13C Relaxation Times ; Prototropic equilibria ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Quaternary 13C dipole-dipole spin-lattice relaxation times are used to analyse prototropic equilibria of 2-acetylbenzimidazole (1) and 4-azabenzimidazole in DMSO-d6 solutions. For the first compound, fast exchange between the two chelated structures prevails for 13C relaxation times, whereas proton and 13C chemical shifts characterize a slow exchange. For 4-azabenzimidazole, 13C and 1H spectra do not exhibit absorptions from structures in slow exchange. Analysis of the T1 values of carbons 8 and 9 before and after isotopic exchange of the labile amino hydrogen clearly show that the major component of the equilibrium is the 3H structure.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260250105
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