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High‐Precision Measurement of 187 Os/ 188 Os Isotope Ratios of Nanogram to Picogram Amounts of Os in Geological Samples by N‐ TIMS using Faraday Cups Equipped with 10 13 Ω Amplifiers
Author(s) -
Wang Guiqin,
Vollstaedt Hauke,
Xu Jifeng,
Liu Wengui
Publication year - 2019
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/ggr.12269
Subject(s) - repeatability , analytical chemistry (journal) , mass fraction , chemistry , isotope , fraction (chemistry) , homogeneous , radiochemistry , chromatography , physics , nuclear physics , organic chemistry , thermodynamics
N ( 187 Os)/ N ( 188 Os) ratios of six geological reference materials were measured using static Faraday cups ( FC s) with 10 13 Ω amplifiers by N‐ TIMS . Our results show that the repeatability precision was 2–3‰ (2 RSD , n = 3), when taking ~ 1 g of BHVO ‐2 with 76 pg g −1 of Os mass fraction and ~ 2 g of BCR ‐2 with 21 pg g −1 of Os mass fraction for each sample, whether measured by FC s or by secondary electron multiplier. The repeatability precision measured by FC s was 1–0.2‰ (2 RSD , n = 3) when taking ~ 1 g of BIR ‐2 with 350 pg g −1 of Os mass fraction, ~ 1 g of WGB ‐1 with 493 pg g −1 of Os mass fraction or ~ 0.5 g of WPR ‐1 with 13.3 ng g −1 of Os mass fraction for each sample, which is much better than those measured by secondary electron multiplier. Instead, when taking ~ 2 g of AGV ‐2 with 4 pg g −1 Os mass fraction, the repeatability precision measured by secondary electron multiplier is 3–4‰ ( RSD , n = 3), which is better than those measured by FC s. Of the six reference materials analysed, WPR ‐1 and BIR ‐1a are the most homogeneous with regard to Os isotopic composition (2 RSD of 0.08% and 0.23%, respectively) when test portion masses are 0.5–1 g.