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  • Analytical Chemistry and Spectroscopy  (2)
  • Growth  (1)
  • 1985-1989  (3)
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 136 (1987), S. 37-48 
    ISSN: 1615-6102
    Keywords: Chara ; Fine structure ; Growth ; Heavy metals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The toxicity of some heavy metals to the common macrophytic freshwater algaChara vulgaris was studied under laboratory conditions. For experiments, apical tips of algae containing two internodes were cultivated for fourteen days in the presence of various concentrations of cadmium, mercury or lead (as triethyl lead or lead nitrate). Fifty percent growth inhibition occurred with concentrations of 8.5×10−8 M (9.5 ppb) cadmium, 7.5×10−7M (150ppb) mercury, 1.6×10−6 M (330ppb) organic lead or 4× 10−5 M (8000 ppb) inorganic lead. Sublethal concentrations of these metals caused alterations in the fine structure of internodal cells which turned out to be at least partly metal-specific or in the case of lead, the effects depended on whether the lead was ionic or organically bound. Cadmium and inorganic lead induced disorders of cell wall microfibrils which resulted in local wall protuberances. Mercury affected the chloroplasts which mostly showed considerably increased grana stacks. In addition, mercury caused a dilation of the endoplasmic reticulum and of the mitochondrial tubuli. Organic lead damaged the membrane system of chloroplasts; sheet- or tubule-like thylakoids were disarranged and showed whorl-like structures. At higher concentrations of organic lead, tubular invaginations of the plasmalemma (“charasomes”) disappeared. The fine structure of nuclei was not altered by any of the metals.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1985), S. 477-488 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The main ionization methods in a mass spectrometer for isotope ratio determinations of the elements are discussed in this review. These methods are thermal ionization, spark source, electron impact, inductively coupled plasma and field desorption. As concerns thermal ionization, electron impact and field desorption, a survey of the possibilities of isotope analyses in the periodic table of the elements is given. Besides kinetic studies, trace element determination by isotope dilution technique is the main application for isotope ratio measurements of the elements. The definitive method, isotope dilution mass spectrometry, is discussed as a potential tool for achieving accurate and precise trace analyses. Using field desorption mass spectrometry, one example of calcium kinetics in man and one example of thallium trace determination in an animal tissue are given. Other metal trace analyses with the isotope dilution technique are presented for biological and medical samples using positive thermal ionization mass spectrometry. Negative thermal ions are formed for the mass spectrometric analysis of non-metals and non-metal compounds in food samples, e.g. for iodine and nitrate in milk powder. Preliminary results with the isotope dilution technique are presented for a new quadrupole thermal ionization mass spectrometer which is a low-cost instrument and can be easily handled.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Fast-atom bombardment, thermal ionization and inductively coupled plasma mass spectrometry are contrasted in comparative measurements of 64Zn/67Zn isotope ratios on samples isolated in the course of a human mineral-nutrition experiment. The data are evaluated with reference to the precision normally required in enriched stable-isotope mineral-nutrition studies, and the convenience of the mass spectrometric techniques is also compared.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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