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*

Röthke, Anita; Görlitz, Volker; Jährling, Reinhard; Kipphardt, Heinrich; Matschat, Ralf; Richter, Silke; Rienitz, Olaf; Schiel, Detlef

doi:10.1088/1681-7575/ab5636

Cited by 1 publication

(2 citation statements)

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“…Whereas Röthke et al [9] summarise the work/comparisons on primary calibration solutions, due to effort and complexity, only very few metrological comparisons [14] have been applied on characterisation of the underlying solid materials. Concerning the evaluation of comparisons of total purity analysis by the difference method, it must be kept in mind that not only the analytical performance of the total purity determination matters, but also their performance for the individual impurities matter, as wrong results for different impurities can mask each other.…”

Section: Status and Perspectivesmentioning

confidence: 99%

“…This can be by the primary difference method (PDM), i.e., by quantifying the analyte indirectly by subtracting the sum of all possible impurities from the ideal purity of 1 kg•kg −1 , or by a classical primary direct method of measurement (CPM), i.e., by quantifying the main analyte directly. The activities on primary standards conducted by the IAWG so far are comprehensively compiled by Röthke et al [9]. It is notable that mainly activities on comparison exercises and studies at least one step further down in the traceability chain than the PTS in the metrological hierarchy are reported, i.e., at the level of calibration solutions that are typically related to (solid) PTS.…”

Section: Introductionmentioning

confidence: 99%

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On the way to SI traceable primary transfer standards for amount of substance measurements in inorganic chemical analysis

et al. 2023

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During its 25 years of existence, the Inorganic Analysis Working Group of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology (CCQM IAWG) has achieved much in establishing comparability of measurement results. Impressive work has been done on comparison exercises related to real-world problems in fields such as ecology, food, or health. In more recent attempts, measurements and comparisons were focused on calibration solutions which are the basis of most inorganic chemical measurements. This contribution deals with the question of how to achieve full and transparent SI traceability for the values carried by such solutions. Within this framework, the use of classical primary methods (CPMs) is compared to the use of a primary difference method (PDM). PDM is a method with a dual character, namely a metrological method with a primary character, based on the bundling of many measurement methods for individual impurities, which lead to materials with certified content of the main component. As in classical methods, where small corrections for interferences are accepted, in PDM, many small corrections are bundled. In contrast to classical methods, the PDM is universally applicable to all elements in principle. Both approaches can be used to certify the purity (expressed as mass fraction of the main element) of a high-purity material. This is where the metrological need of National Metrology Institutes (NMIs) for analytical methods meet the challenges of analytical methods. In terms of methods, glow discharge mass spectrometry (GMDS) with sufficient uncertainties for sufficiently small impurity contents is particularly noteworthy for the certification of primary transfer standards (PTS), and isotope dilution mass spectrometry (IDMS), which particularly benefits from PTS (back-spikes) with small uncertainties, is particularly noteworthy for the application. The corresponding relative uncertainty which can be achieved using the PDM is very low (< 10−4). Acting as PTS, they represent the link between the material aspect of the primary calibration solutions and the immaterial world of the International System of Units (SI). The underlying concepts are discussed, the current status of implementation is summarised, and a roadmap of the necessary future activities in inorganic analytical chemistry is sketched. It has to be noted that smaller measurement uncertainties of the purity of high-purity materials not only have a positive effect on chemical measurements, but also trigger new developments and findings in other disciplines such as thermometry or materials science. Graphical Abstract Primary Transfer Standards (PTSs) are the link between the immaterial world of the International System of Units (SI) and the material aspects of the primary calibration solutions.

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Section: Status and Perspectivesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%