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Realization of SI traceability for Mg isotope amount ratios & delta values

  • In isotope ratio applications metrological principles such as measurement uncertainty and SI traceability often are not considered or realized. This is also well-documented by the traceability exception related to delta scale isotope ratio measurements CCQM requested from the CIPM. Generally, delta scale isotope ratio measurements can be performed on a precision level that is significantly lower than the uncertainty level of isotope amount ratio measurements. In the case of magnesium, we demonstrated for the first time that isotope amount ratios can be measured with uncertainties close to the typical precision of magnesium delta values, δ26/24Mg, which are at the 0.1 ‰ level. In the past, δ26/24Mg measurements were referenced to NIST SRM 980, the initial zero of the δ26/24Mg scale. With the development of MC-ICPMS, the detection of small but measurable isotopic differences in different chips of NIST SRM 980 became apparent and NIST SRM 980 was replaced by an intermediate artefact,In isotope ratio applications metrological principles such as measurement uncertainty and SI traceability often are not considered or realized. This is also well-documented by the traceability exception related to delta scale isotope ratio measurements CCQM requested from the CIPM. Generally, delta scale isotope ratio measurements can be performed on a precision level that is significantly lower than the uncertainty level of isotope amount ratio measurements. In the case of magnesium, we demonstrated for the first time that isotope amount ratios can be measured with uncertainties close to the typical precision of magnesium delta values, δ26/24Mg, which are at the 0.1 ‰ level. In the past, δ26/24Mg measurements were referenced to NIST SRM 980, the initial zero of the δ26/24Mg scale. With the development of MC-ICPMS, the detection of small but measurable isotopic differences in different chips of NIST SRM 980 became apparent and NIST SRM 980 was replaced by an intermediate artefact, DSM3. To solve this problem a suite of magnesium isotope reference materials, ERM-AE143, -AE144, and -AE145, has been certified in a first study by applying an ab initio calibration for absolute Mg isotope ratios without any a priori assumptions, a procedure which fulfils all requirements of a primary method of measurement. Thus, these materials qualified to establish SI-traceability for magnesium delta measurements. In a second study five expert laboratories participated to cross-calibrate all available magnesium isotope standards, which are NIST SRM 980, IRMM-009, ERM-AE143, ERM-AE144, ERM-AE145 and the standards DSM3 and Cambridge-1. The mean δ26/24Mg values for the individual iRMs, calculated from the laboratory means show 2 SD reproducibilities varying between 0.025 and 0.093 ‰. Propagated measurement uncertainties suggest a standard uncertainty of about 0.1 ‰ for δ26/24Mg determinations. Thus, SI traceability for magnesium isotope amount ratios and delta values is demonstrated to be established.zeige mehrzeige weniger

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Autor*innen:Jochen VoglORCiD
Koautor*innen:O. Rienitz, M. Rosner, B. Brandt, S. A. Kasemann, R. Kraft, D. Malinovskiy, A. Meixner, J. Noordmann, S. Rabb, J. A. Schuessler, R. D. Vocke
Dokumenttyp:Posterpräsentation
Veröffentlichungsform:Präsentation
Sprache:Englisch
Jahr der Erstveröffentlichung:2019
Organisationseinheit der BAM:1 Analytische Chemie; Referenzmaterialien
1 Analytische Chemie; Referenzmaterialien / 1.1 Anorganische Spurenanalytik
DDC-Klassifikation:Naturwissenschaften und Mathematik / Chemie / Analytische Chemie
Freie Schlagwörter:Delta values; Isotope amount ratio; Magnesium; SI traceability
Themenfelder/Aktivitätsfelder der BAM:Chemie und Prozesstechnik
Veranstaltung:CCQM Workshop on "Advances in Metrology in Chemistry and Biology"
Veranstaltungsort:Sèvres, France
Beginndatum der Veranstaltung:09.04.2019
Enddatum der Veranstaltung:10.04.2019
Verfügbarkeit des Dokuments:Datei im Netzwerk der BAM verfügbar ("Closed Access")
Datum der Freischaltung:13.05.2019
Referierte Publikation:Nein
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