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Neutron activation determination of iridium, gold, platinum, and silver in geologic samples

Journal of Radioanalytical and Nuclear Chemistry Articles

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DOI: 10.1007/BF02036054

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Abstract

Low-level methods for the determination of iridium and other noble metals have become increasingly important in recent years due to interest in locating abundance anomalies associated with the Cretaceous and Tertiary (K-T) boundary. Typical iridium anomalies are in the range of 1 to 100 ??g/kg (ppb). Thus methods with detection limits near 0.1 ??g/kg should be adequate to detect K-T boundary anomalies. Radiochemical neutron activation analysis methods continue to be required although instrumental neutron activation analysis techniques employing elaborate gamma-counters are under development. In the procedure developed in this study samples irradiated in the epithermal neutron facility of the U. S. Geological Survey TRIGA Reactor (Denver, Colorado) are treated with a mini-fire assay technique. The iridium, gold, and silver are collected in a 1-gram metallic lead button. Primary contaminants at this stage are arsenic and antimony. These can be removed by heating the button with a mixture of sodium perioxide and sodium hydroxide. The resulting 0.2-gram lead bead is counted in a Compton suppression spectrometer. Carrier yields are determined by reirradiation of the lead beads. This procedure has been applied to the U.S.G.S. Standard Rock PCC-1 and samples from K-T boundary sites in the Western Interior of North America. ?? 1987 Akade??miai Kiado??.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Neutron activation determination of iridium, gold, platinum, and silver in geologic samples
Series title:
Journal of Radioanalytical and Nuclear Chemistry Articles
DOI:
10.1007/BF02036054
Volume
113
Issue:
1
Year Published:
1987
Language:
English
Publisher location:
Kluwer Academic Publishers
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Journal of Radioanalytical and Nuclear Chemistry Articles
First page:
125
Last page:
132
Number of Pages:
8