The precise measurement of Tl isotopic compositions by MC-ICPMS: Application to the analysis of geological materials and meteorites
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Geological Sciences
The precision of Tl isotopic measurements by thermal ionization mass spectrometry (TIMS) is severely limited by the fact that Tl possesses only two naturally occurring isotopes, such that there is no invariant isotope ratio that can be used to correct for instrumental mass discrimination. In this paper the authors describe new chemical and mass spectrometric techniques for the determination of Tl isotopic compositions at a level of precision hitherto unattained. Thallium is first separated from the geological matrix using a two-stage anion-exchange procedure. Thallium isotopic compositions are then determined by multiple-collector inductively coupled plasma-mass spectrometry with correction for mass discrimination using the known isotopic composition of Pb that is admixed to the sample solutions. With these procedures they achieve a precision of 0.01--0.02% for Tl isotope ratio measurements in geological samples and this is a factor of {ge}3--4 better than the best published results by TIMS. Results are discussed for five terrestrial samples and for the C3V chondrite Allende.
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- OSTI ID:
- 355674
- Journal Information:
- Geochimica et Cosmochimica Acta, Vol. 63, Issue 6; Other Information: PBD: Mar 1999
- Country of Publication:
- United States
- Language:
- English
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