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  • Chemistry  (1)
  • IDMS  (1)
  • Brassicaceae
  • Larix
  • Organic Chemistry
  • R/V Vereshchagin
  • calculation
  • 2000-2004  (2)
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  • 1
    ISSN: 1432-0517
    Schlagwort(e): Key words PERM ; ICP-MS ; PTI-MS ; IDMS ; Uncertainty budget ; Certification ; Polyethylene
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie
    Notizen: Abstract  The present paper describes the certification of the amount content of Cd, Cr and Pb in two different polyethylene materials within the third phase of the Polyethylene Elemental Reference Material (PERM) project. The analytical procedure to establish the reference values for Cd, Cr and Pb amount contents in these materials is based on isotope dilution mass spectrometry used as a primary method of measurement. Cd and Pb were measured with inductively coupled plasma-mass spectrometry and Cr with positive thermal ionization-mass spectrometry. The decomposition of the polymer matrix was carried out using a high pressure asher. Reference values for amount content, traceable to the SI-system, have been obtained for these three elements in both of the polyethylene samples of PERM. For each of the certified amount content values an uncertainty budget was calculated using the method of propagation of uncertainties according to ISO and EURACHEM guidelines. The measurement procedures, as well as the uncertainty calculations, are described for all three elements. In order to keep the whole certification process as transparent as possible, the preparations of various reagents and materials as well as the sample treatment and blending are described in detail. The mass spectrometry measurements and the data treatment are also explained carefully. The various sources of uncertainty present in the procedure are displayed in the uncertainty budgets. The obtained combined uncertainties for the amount content values were less than 2% relative (k=1) for all investigated elements. The amount contents were in the μmol/kg range, corresponding to mg/kg levels.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 2000 (2000), S. 837-840 
    ISSN: 1434-193X
    Schlagwort(e): Chiral auxiliaries ; Analytical methods ; Through-space interactions ; Lactic acid ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: ---The enantiomeric purity of a chiral compound is determined by NMR spectroscopic analysis of the diastereomers formed with a chiral derivatizing agent. Fluorinated O-aryllactic acids (FAC) 1 are efficient chiral reporters, whose spectacular remote anisotropic effects allow an easy identification and measurement of diastereomers. The remote effects are attributed to the particular design of FAC esters relative to other CDAs.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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