Berlin 2014 – wissenschaftliches Programm
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MS: Fachverband Massenspektrometrie
MS 1: New Mass Spectrometric Methods and Technical Developments
MS 1.2: Vortrag
Montag, 17. März 2014, 11:00–11:15, DO24 1.205
MC-ICP-MS vs. IRMS: Advantages and Limits in Case of Isotopic Enriched Silicon — •Axel Pramann1, Janine Noordmann1, Olaf Rienitz1, Helmut Beckers2, and Helge Willner2 — 1Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig, Germany — 2Bergische Universität Wuppertal, Gaussstr. 20, 42097 Wuppertal, Germany
The scheduled redefinition of the Si unit kilogram is connected to the determination of the Avogadro constant with smallest associated uncertainty.[1] Mass Spectrometry on the highest metrological level is used to measure the molar mass of a silicon material enriched in 28Si.[2] We report on the advantages and improvements using high resolution multicollector-ICP-MS to measure that material. A new advancement of an analytical approach of mass bias correction in isotope ratio measurement, resulted in a strong reduction of the uncertainty associated with M down to a relative uncertainty of 6.1 x 10-9. The uncertainty budget and main features of the new theory for correction (K) factor determination are given. For calibration purposes of an isotope ratio gas mass spectrometer (IRMS) this Si material was converted into silicon tetrafluoride and further investigated with respect to the isotopic composition of silicon. The limits and improvements compared to the complementary MC-ICP-MS method are presented.
[1] B. Andreas et al., Metrologia, 48, S1 (2011).
[2] A. Pramann, O. Rienitz, D. Schiel, J. Schlote, B. Güttler, and S. Valkiers, Metrologia 48, S20 (2011).