Osmium isotopic compositions by vapor phase sample introduction using a multi-collector ICP-MS

Osmium isotopic compositions have been measured using a vapor phase sample introduction technique in which volatile OsO₄ is sparged directly into a multi-collector ICP-MS for analysis. Replicate analyses of an in-house solution standard yield an average ¹⁸⁸Os/¹⁹²Os value that is within 10 ppm of the accepted natural value when corrected for mass discrimination using ¹⁸⁹Os/¹⁹²Os, with a reproducibility of ±0.5 permil (2 SE, □ = 9) for samples containing 10 ng of Os. The average ¹⁸⁷Os/¹⁹²Os measured for this solution agrees with the value determined by negative thermal ionization mass spectrometry to <1 permil, with a precision of ±1.5 permil (2 SE). Vapour phase analysis of Os isotopic compositions by MC-ICP-MS is applicable to a variety of geological and environmental studies.