Yokoyama et al. (2001) Precise analysis of 234U/238U ratio using UO2+ ion with thermal ionization mass spectrometry for natural samples, Chemical Geology, 181, 1-12, doi:10.1016/S0009-2541(01)00270-4. < 20200424110458-827721 > pub
  • abstract:

    We have developed a new, highly precise method for U isotopic analysis using a thermal ionization mass spectrometry (TIMS) by measuring UO2+ ions emitted from a very small amount (100–10 ng) of U. A new ionization activator, a silicic acid–diluted phosphoric acid solution, was found to be effective not only for producing a strong and stable UO2+ ion beam, but also for keeping the mass fractionation during measurement small and constant. U isotope analysis was carried out by a “dynamic multi collection” method using three Faraday cup collectors and a secondary electron multiplier in ion counting mode with RPQ (RPQ-SEM). For precise isotope analysis, baselines of the Faraday cups and a conversion factor between Faraday cups and the RPQ-SEM were precisely determined simultaneously with U isotope collection. Analytical precision and reproducibility of 234U/238U ratio ranged from 0.10% to 0.38% (2σmean) and from 0.13% to 0.31% (2σ), respectively, for 100–10 ng of U extracted from a natural rhyolitic obsidian. The precision and reproducibility were improved compared with previous studies, and thus, our method is especially useful for samples with very low abundance of U.

  • doi: 10.1016/S0009-2541(01)00270-4
  • modified at 2020-04-24
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  • name
  • Yokoyama, Tetsuya
  • Makishima, Akio
  • Nakamura, Eizo