Final report of the key comparison CCQM-K72: Purity of zinc with respect to six defined metallic analytes

Abstract

/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr READ THESE TERMS AND CONDITIONS CAREFULLY BEFORE USING THIS WEBSITE.http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en Vous avez des questions? Nous pouvons vous aider. Pour communiquer directement avec un auteur, consultez la première page de la revue dans laquelle son article a été publié afin de trouver ses coordonnées. Si vous n'arrivez pas à les repérer, communiquez avec nous à PublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. Questions? Contact the NRC Publications Archive team atPublicationsArchive-ArchivesPublications@nrc-cnrc.gc.ca. If you wish to email the authors directly, please see the first page of the publication for their contact information. NRC Publications Archive Archives des publications du CNRCFor the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://doi.org/10.1088/0026-1394/51/1A/08008 Metrologia, 51, 1A, 2014-01-01 CCQM-K72 Purity of Zinc with respect to six defined metallic analytes MotivationHigh purity elements can serve as a realisation of the SI unit amount of substance for the specific element. Solutions prepared from high purity metals by applying gravimetric preparation and the concept of molar mass are used as 'calibration' solutions in many fields of analytical chemistry and provide the metrological basis in elemental analysis. Since ideal purity does not exist for real materials, the actual purity of the high purity material must be known with a specified uncertainty. Such purity data, however, are only accessible via measurements, which are limited by their measurement uncertainty. Aiming at uncertainties around 10 -4relative on the purity statement in almost all cases a direct measurement of the element in itself is not applicable, because the available methods are not sufficiently selective and/or accurate. Therefore the indirect approach is followed in order to achieve uncertainties at this level. In the indirect approach the mass fractions of all impurities, in other words all elements excepting the matrix element, are measured and their sum is subtracted from the value for ideal purity, which is 1 kg/kg. Uncertainties at the 10 -4 level are aimed at because high purity metals are not only destined for being used as convenient primary realisations of the SI unit, but also as primary assays or so-called back-spikes in double isotope dilution mass spectrometry (IDMS). With double IDMS combined uncertainties down to 5·10 -4 can be achieved and therefore the uncertainty on the purity statement for these materials should be at or even lower than 10 -4 relative in order not to compromise the IDMS results.As a first step, only six metallic impurities are considered in previous studies and also in this comparison, in order to limit the effort within this study. Other metallic and non-metallic impurities might be subject to future CCQM studies. Zinc was chosen as matrix, due to its ease of...

SI-traceable monoelemental solutions on the highest level of accuracy: 25 years from the foundation of CCQM to recent advances in the development of measurement methods*

“…The results of CCQM-P107 were much better compared to the earlier study CCQM-P62. While in CCQM-P62 the results differed by a factor of 8, in CCQM-P107 the spread was less than 30% [15]. Thus, the IAWG decided to finally conduct a corresponding key comparison and parallel pilot study coordinated again by BAM in 2012: CCQM-K72/P107.1 'Purity of zinc with respect to six defined metallic analytes'.…”

Establishing comparability and compatibility in the purity assessment of high purity zinc as demonstrated by the CCQM-P149 intercomparison

“…As a consequence, total purity measurements remain a long-term strategy of the Inorganic Analysis Working Group (IAWG) within the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM). As a first step, intercomparisons CCQM-P107 [3] and CCQM-K72 & P107.1 [4] were conducted on the determination of the purity of zinc with respect to six defined metallic impurities. Zinc was chosen as the matrix because it is considered to be a comparatively easy matrix but of high relevance.…”

“…F26S010). The same three ingots which had earlier been used for CCQM-K72 [4] were also used for CCQM-P149. The Zn ingots were cut into pieces of approximately 20 g. As the geometry of the ingots varied slightly, the resulting pieces showed a bar geometry with a diameter of 8 mm to 10 mm and a length between 35 mm and 45 mm.…”

“…Investigations of the homogeneity of the material were already made for CCQM-K72 [4]. GD-MS measurements showed a spread of the results of < 20 % relative for Al, Ag, Cd, Cr, Ni and Tl, rendering the material suitable for CCQM-K72.…”

Determination of Ultra-trace Metal Impurities in High-purity Cadmium Using Inductively Coupled Plasma Mass Spectrometry after Matrix Separation with Anion Exchange Resin

“…In order to establish the comparability for purity assessment among national metrology institutes (NMIs), international comparisons have been carried out. According to the international comparisons such as CCQM-P107 (2009), CCQM-K72 (2013) and CCQM-P149 (2015) 3,4 organized by the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM), 5 most of the participants of NMIs use the subtraction method, which is carried out by impurity analysis, to evaluate the purity of high-purity materials.…”