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New Thorium Isotope Ratio Measurements in Silicate Reference Materials: A‐ THO , AGV ‐2, BCR ‐2, BE ‐N, BHVO ‐2 and BIR ‐1
Author(s) -
Carpentier Marion,
Gannoun Abdelmouhcine,
Pin Christian,
Sigmarsson Olgeir
Publication year - 2016
Publication title -
geostandards and geoanalytical research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.037
H-Index - 73
eISSN - 1751-908X
pISSN - 1639-4488
DOI - 10.1111/j.1751-908x.2015.00385.x
Subject(s) - thorium , physics , chemistry , analytical chemistry (journal) , chromatography , radiochemistry , mineralogy , nuclear physics , uranium
A two‐step Th isolation protocol, involving micro‐columns of TRU ‐Spec extraction chromatography material and AG 1 resin, was evaluated. The MC ‐ ICP ‐ MS procedure included 232 Th tailing characterisation and correction, and calibrator bracketing using an in‐house standard solution (ThS1) to correct for instrumental mass bias and Faraday cup to secondary electron multiplier relative gain. Repeated analyses of reference solutions ( UCSC Th ‘A’, WUN , OU Th ‘U’, IRMM ‐36) were consistent with published data. Six reference materials (A‐ THO , BCR ‐2, AGV ‐2, BHVO ‐2, BE ‐N and BIR ‐1) were processed. The average 230 Th/ 232 Th values obtained for these samples are in excellent agreement with published data. In addition, we report the first 230 Th/ 232 Th values for BE ‐N and BIR ‐1. The intermediate precisions for rock samples ranged from ± 0.24 to ± 0.49% (2 RSD ) and were similar to those achieved for synthetic solutions, thereby supporting the overall validity of the chemical separation, data acquisition and reduction procedures. Counting statistics on the 230 Th isotope was the most significant source of uncertainty. The intermediate precision of the mean 230 Th/ 232 Th for the Th‐depleted BIR ‐1 (5.64 × 10 −6 ± 0.27%, 2 RSD ) is in the range of the analyses of other reference materials analysed in this study.