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- 저자 : Rienitz, O (검색결과 3 건)
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Probing the homogeneity of the isotopic composition and molar mass of the ‘Avogadro’-crystal
Pramann, Axel,Lee, Kyoung-Seok,Noordmann, Janine,Rienitz, Olaf IOP 2015 METROLOGIA -BERLIN- Vol.52 No.6
<P>Improved measurements on silicon crystal samples highly enriched in the Si-28 isotope (known as 'Si28' or AVO28 crystal material) have been carried out at PTB to investigate local isotopic variations in the original crystal. This material was used for the determination of the Avogadro constant N-A and therefore plays an important role in the upcoming redefinition of the SI units kilogram and mole, using fundamental constants. Subsamples of the original crystal have been extensively studied over the past few years at the National Research Council (NRC, Canada), the National Metrology Institute of Japan (NMIJ, Japan), the National Institute of Standards and Technology (NIST, USA), the National Institute of Metrology (NIM, People's Republic of China), and multiple times at PTB. In this study, four to five discrete, but adjacent samples were taken from three distinct axial positions of the crystal to obtain a more systematic and comprehensive understanding of the distribution of the isotopic composition and molar mass throughout the crystal. Moreover, improved state-of-the-art techniques in the experimental measurements as well as the evaluation approach and the determination of the calibration factors were utilized. The average molar mass of the measured samples is M = 27.976 970 12(12) g mol(-1) with a relative combined uncertainty u(c,rel)(M) = 4.4 x 10(-9). This value is in astounding agreement with the values of single samples measured and published by NIST, NMIJ, and PTB. With respect to the associated uncertainties, no significant variations in the molar mass and the isotopic composition as a function of the sample position in the boule were observed and thus could not be traced back to an inherent property of the crystal. This means that the crystal is not only 'homogeneous' with respect to molar mass but also has predominantly homogeneous distribution of the three stable Si isotopes.</P>
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Final report on CCQM-K89: Trace and essential elements in Herba Ecliptae
Valiente, Liliana,Saxby, David,Merrick, Jeffrey,Kotzeva, Boriana,Mester, Zoltan,Yang, Lu,Willie, Scott,Feng, Liuxing,Wang, Jun,Labarraque, Guillaume,Rienitz, Olaf,Wai-mei Sin, Della,Mok, Chuen-sing,Wo Springer-Verlag 2013 Metrologia Vol.50 No.-
<P>The key comparison CCQM-K89 was undertaken to demonstrate the capability of participating NMIs and DIs in measuring the contents of incurred trace elements (total arsenic, cadmium and lead) and essential elements (calcium and zinc) at µg/g (for arsenic, cadmium, lead and zinc) and mg/g (for calcium) levels in a herb matrix sample by various analytical techniques.</P><P>This key comparison was organized by the Government Laboratory of the Hong Kong Special Administrative Region (GLHK) and agreed at the Inorganic Analysis Working Group Meeting in Hindås, Sweden in October 2010 as a benchmarking exercise with arsenic (a trace element) and calcium (an essential element) chosen as the 'exemplary' elements. It was also agreed that a pilot study CCQM-P126 would be run in parallel with this key comparison.</P><P>The key comparison serves to facilitate claims by participants on the Calibration and Measurement Capabilities (CMCs) as listed in Appendix C of the Key Comparison Database (KCDB) under the Mutual Recognition Arrangement of the International Committee for Weights and Measures (CIPM MRA).</P><P>A total of 20 NMIs/DIs registered for this programme and 18 of them submitted their results. Most of the participants used microwave acid digestion methods for sample dissolution. For the instrumental determination, a variety of techniques like ICP-MS, AAS, INAA, ICP-AES were employed by the participants. For this key comparison, inorganic core capabilities have been demonstrated by concerned participants with respect to methods including ICP-MS (without isotope dilution), ID-ICP-MS, ICP-AES, INAA, AAS and ion chromatography with iteratively matrix-matched calibration on the determination of total arsenic, calcium, cadmium, lead and zinc in a matrix of herb.</P><P>Main text.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/.</P><P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>
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Final report on CCQM-K125: elements in infant formula
Merrick, J,Saxby, D,Dutra, E S,Sena, R C,Araú,jo, T O,Almeida, M D,Yang, L,Pihillagawa, I G,Mester, Z,Sandoval, S,Wei, C,Castillo, M E D,Oster, C,Fisicaro, P,Rienitz, O,Pape, C,Schulz, U,Jä BUREAU INTERNATIONAL DES POIDS ET MESURES 2017 METROLOGIA -BERLIN- Vol.54 No.1
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