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J. Vogl D. Liesegang M. Ostermann J. Diemer M. Berglund C. R. Quétel P. D. P. Taylor K. G. Heumann 《Accreditation and quality assurance》2000,5(8):314-324
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.
Received: 21 October 1999 / Accepted: 29 January 2000 相似文献
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