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- 2001 (6) (entfernen)
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- ICP-MS (2)
- IDMS (2)
- Certification (1)
- Reference material (1)
- Surface analysis (1)
- TIMS (1)
- multi-collector (1)
- reference material (1)
- uncertainty budget (1)
A thin-layer reference material for surface and near-surface analytical methods was produced and certified. The surface density of the implanted Sb layer was determined by Rutherford backscattering spectrometry (RBS), instrumental neutron activation analysis (INAA), and inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) equipped with a multi-collector. The isotopic abundances of Sb (121Sb and 123Sb) were determined by multi-collector ICP-MS and INAA. ICP-IDMS measurements are discussed in detail in this paper. All methods produced values traceable to the SI and are accompanied by a complete uncertainty budget. The homogeneity of the material was measured with RBS. From these measurements the standard uncertainty due to possible inhomogeneities was estimated to be less than 0.78% for fractions of the area increments down to 0.75 mm2 in size. Excellent agreement between the results of the three different methods was found. For the surface density of implanted Sb atoms the unweighted mean value of the means of four data sets is 4.8121016 cm-2 with an expanded uncertainty (coverage factor k=2) of 0.0921016 cm-2. For the isotope amount ratio R (121Sb/123Sb) the unweighted mean value of the means of two data sets is 1.435 with an expanded uncertainty (coverage factor k=2) of 0.006.
Hochpräzise Bestimmung von Cadmium und Blei in Sedimentproben im Rahmen von CCQM-Ringversuchen
(2001)
A comparison of different isotope dilution mass spectrometric (IDMS) procedures using inductively coupled plasma mass spectrometry (ICPMS) and thermal ionization mass spectrometry (TIMS) was carried out to examine the degree of equivalence between the used procedures in terms of requirements for reference material certification. The comparison was based on the measurement results and their uncertainties. The sample used in this study is a pure zinc metal to be certified by the Bureau Communie de Référence (BCR) for amount contents of different trace elements. This study focuses on cadmium and thallium. The TIMS values contributed to the certified values. To guarantee identical conditions as far as possible for the procedures under investigation, the samples were split into subsamples after spiking and digestion took place. Thus, every IDMS procedure started with an identical set of samples. In total, four different IDMS procedures and one external calibration procedure using internal standardization as an example of routine analysis were applied. The IDMS procedures divide in a group with and a group without trace/matrix separation. Multicollector TIMS (TI-MC-MS) and multicollector ICPMS (ICP-MC-MS) were used in combination with trace/matrix separation, whereas quadrupole ICPMS (ICP-QMS) and ICP-MC-MS were also applied to nonseparated samples. All IDMS results agree well within their combined uncertainties, while some results from the external calibration procedure do not. IDMS results obtained by ICPMS without separation are comparable to those obtained by TI-MC-MS with separation regarding precision and accuracy. The smallest uncertainties were achieved using ICP-MC-MS in combination with trace/matrix separation.
The neutron transmutation doping (NTD) of highly pure copper with zinc was investigated as a promising means of achieving controlled gradation of the zinc content in the range 1-20 wg g-1. The doping process leads to the enrichment of two stable isotopes 64Zn and 66Zn in a ratio which differs from that of natural isotopic distribution. Mass spectrometric investigations by thermal ionization mass spectrometry (TIMS) were performed to validate the results obtained by gamma spectrometry. The investigations included both determination of the isotopic ratios of the doped zinc isotopes and the analysis of the accumulated zinc contents by isotope dilution (ID) analysis. Thereby a sample-specific correction of the blank could be performed because the isotope 68Zn was not influenced, because of the transmutation process. The results obtained by TIMS prove the strict proportionality of the doped zinc content, in the range 5 to 20 wg g-1, to the neutron fluence. Comparison with gamma spectrometric results showed a very good agreement within the uncertainties.