title: Determination of radium isotope ratios and abundances in geologic samples by thermal ionization mass spectrometry.
abstract: We describe chemical separation and mass spectrometric procedures for the measurement of radium isotopes in geologic samples. These methods provide 226Ra/228Ra ratio measurements for 1 g or less of rock sample containing subpicogram amounts of radium with precision better than 1.5% (95% confidence level). Radium-226 concentrations were measured by isotope dilution for smaller sample sizes (100-500 mg) containing as little as 1-10 fg of total 226Ra with similar high precision.
authors.affiliation: Isotope Geochemistry, Los Alamos National Laboratory, New Mexico 87545.
authors.forename: A M
authors.initials: AM
authors.lastname: Volpe
authors.forename: J A
authors.initials: JA
authors.lastname: Olivares
authors.forename: M T
authors.initials: MT
authors.lastname: Murrell
mesh_terms: D005844:Geology / Q000379:methods; D007554:Isotopes; D013058:Mass Spectrometry / Q000379:methods; D011883:Radium / Q000032:analysis*
chemical_list: D007554:Isotopes; D011883:Radium