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  • Analytical Chemistry and Spectroscopy  (4)
  • Aquatic systems  (2)
  • Collective Choice
  • C72
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Geologische Rundschau 85 (1996), S. 29-37 
    ISSN: 0016-7835
    Keywords: Key words Banded mineralization ; Harz mountains ; Self-organization ; Iron ; manganese ; ferrihydrite ; birnessite ; Time-series analysis ; Aquatic systems ; Iron bacteria ; Ostwald ripening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  A recent early diagenetic banded iron–manganese mud has been forming underground in a closed lead–zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    International journal of earth sciences 85 (1996), S. 29-37 
    ISSN: 1437-3262
    Keywords: Banded mineralization ; Harz mountains ; Self-organization ; Iron, manganese, ferrihydrite, birnessite ; Time-series analysis ; Aquatic systems ; Iron bacteria ; Ostwald ripening
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A recent early diagenetic banded iron-manganese mud has been forming underground in a closed lead-zinc mine for approximately 40 years. The processes leading to the banded structure of the precipitate were studied during a period of 2 years. Therefore, 19 physical and chemical parameters were measured regularly in short intervals. The resulting time series were analysed with respect to the data sets of the monthly chemical analyses of the descendent mine water, the daily rainfall and the mineral content. The results reveal that the precipitated material undergoes internal self-organization due to interaction of redox, colloid-chemical, microbial, electrical and ripening processes, and not exclusively produced by seasonal fluctuations of material input. Thus, the primary banding of the material, caused by externally forced fluctuations of the redox conditions within the mine water, is reorganized after a short time. The finally observed bands are controlled by non-linear coupling of reaction and transport processes within the mud. A genetic model for the banded mineralization was developed and verified by numerical simulation.
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  • 3
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Numerous monofunctional amines have been reacted with dimethylthiophosphinic chloride to form stable derivatives. Their good gas chromatographic properties and abundant molecular ions afforded highly sensitive and specific detection by selected ion monitoring (SIM) down to the picogram level. Based upon this derivatization procedure, new methods for the determination of aniline in serum and urine by SIM were developed. The minimum detectable concentration of aniline was 500 pg ml-1. Linear response curves were obtained from 1.5 to 150 ng ml-1 using (2H5)aniline as the internal standard. Specific derivatization of a series of bifunctional amines was achieved with methyldichlorophosphine and sulfur resulting in the formation of stable phospholidine-thiones. These derivatives chromatograph well on nonpolar stationary phases, and their mass spectra exhibit abundant molecular ions. This derivatization reaction was applied to the quantification of ephedrine from urine and serum by SIM with (2H2)ephedrine as the internal standard. The detection limit of the method was 1 ng ml-1. The linearity was established in the range from 10 to 160 ng ml-1.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1978), S. 302-311 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of 20 differently substituted dimethylthiophosphinic esters of aromatic hydroxy compounds are presented. Fragmentation routes were investigated using high resolution mass measurements, decoupled metastable determinations and deuterium labelling. All compounds exhibited abundant molecular ions and typical phosphorus-containing ions. Characteristic elimination processes strongly dependent upon the respective type of substitution were observed. Due to their high stability, their great ease of formation and their good gas chromatographic properties these new types of derivatives are of special interest for establishing gas chromatography mass spectrometry profiles of acidic catecholamine metabolites.
    Additional Material: 2 Ill.
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  • 5
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mass spectra of the dimethylphosphinic, dimethylthiophosphinic and dimethylphosphinous ester derivatives of several monohydroxy steroids are reported. The fragmentations of the derivatized steroids largely depend on the nature of the the phosphorus-containing ester group. Phenolic ester derivatives exhibit the base peak at the molecular ion, whereas the spectra of the secondary phosphinic esters are dominated by very intense protonated phosphinic acid ions [Me2 P(XH)(OH)]+ at m/e 95 (X = O) or at m/e 111 (X = S). The present results also indicate the low ionization potential for the phosphinic ester group. Due to their good gas chromatographic properties, these steroid derivatives appear to be particularly suitable for gas chromatographic mass spectrometric analysis of biochemical materials.
    Additional Material: 4 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 3 (1980), S. 85-86 
    ISSN: 0935-6304
    Keywords: Liquid chromatography, HPLC ; Ion-pair reversed-phase ; Free porphyrin carboxylic acids in urine, complete separation ; Quantitation within 4.4-5.4% precision ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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