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Chemical Separation of Tungsten and Other Trace Elements for TIMS Isotope Ratio Measurements Using Organic Acids
Author(s) -
Peters Bradley J.,
MundlPetermeier Andrea,
Horan Mary F.,
Carlson Richard W.,
Walker Richard J.
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.12259
Subject(s) - reagent , matrix (chemical analysis) , isotope , fraction (chemistry) , chemistry , analytical chemistry (journal) , chromatographic separation , chromatography , physics , organic chemistry , high performance liquid chromatography , quantum mechanics
One requirement for isotope ratio measurement results with small measurement uncertainties is that the element of interest is effectively separated from the sample matrix. Efficient chemical separation of W from matrix components, especially Ti, can be challenging, particularly for large test portion masses (> 1 g). We present a new W separation procedure that takes advantage of the distinct complexation behaviour of Ti and W with citrate ligand in a moderately low pH , oxidising solution. This preparation procedure can reduce the Ti/W ratio of large (4–10 g) basaltic (i.e., high‐matrix) test portions by a factor of 10 5 , relative to their original compositions, in a two‐step separation procedure. The procedure additionally provides a separate, well‐purified Mo fraction. We show that optimal separation requires precise selection of reagent concentrations and sample load. The procedure was employed to determine the μ 182 W composition of BHVO ‐2 as −6.7 ± 4.2 (2 standard deviation, 2 s ). The principles derived from this method may prove useful for chemical separation of other elements used for geochemical and cosmochemical applications given an appropriate selection of organic acid. Future successful applications of this method may reveal that the use of organic acids as procedural reagents is a currently under‐utilised tool for efficient chemical separation protocols.