Determination of radium isotope ratios and abundances in geologic samples by thermal ionization mass spectrometry.

@article{Volpe1991DeterminationOR,
  title={Determination of radium isotope ratios and abundances in geologic samples by thermal ionization mass spectrometry.},
  author={Alan M Volpe and Jos{\'e} A Olivares and Michael T. Murrell},
  journal={Analytical chemistry},
  year={1991},
  volume={63 9},
  pages={913-6}
}
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.