Pushing Limits of ICP-MS/MS for the Determination of Ultralow (236)u/U-238 Isotope Ratios

Author(s)

Hugo Jaegler, Alkiviadis Gourgiotis, Peter Steier, Robin Golser, Olivier Diez, Charlotte Cazala

Abstract

Determination of uranium isotope ratios is of great expedience for assessing its origin in environmental samples. In particular, the U-236/U-238 isotope ratio provides a powerful tool to discriminate between the different sources of uranium (uranium ore, geochemical background, and uranium from anthropogenic activities). However, in the environment, this ratio is typically below 10(-8). This low abundance of U-236 and the presence in large excess of major isotopes (mainly U-238 and U-235) complicates the accurate detection of U-236 signal by mass spectrometry and thus highly sensitive analytical instruments providing high abundance sensitivity are required. This work push es the limits of triple quadrupole-based ICP -MS technology for accurate detection of U-236/U-238 isotope ratios down to 10(-10), which is so far mainly achievable by AMS. Coupled with an efficient desolvating module, N2O was used as the reaction gas in the collision reaction cell of the ICP-MS/MS. This configuration allows a significant decrease of the uranium polyatomic interferences ((UH+)-U-235 ions) and an accurate determination of low U-236/U-238 isotope ratios. This new methodology was successfully validated through measurements of certified reference material from 10(-7) to 10(-9) and then through comparisons with AMS measurement results for ratios down to 10(-10). This is the first time that U-218/U-238 isotope ratios as low as 10(-10) were determined by ICP-MS/MS. The possibility of measuring U-236/U-238 isotope ratios can offer a large variety of geochemical applications in particular for the determination of uranium sources in the environment.

Organisation(s)

Isotope Physics

External organisation(s)

IRSN, PSE ENV SEDRE LELI

Journal

Analytical Chemistry

Volume

92

Pages

7869-7876

No. of pages

8

ISSN

0003-2700

DOI

https://doi.org/10.1021/acs.analchem.0c01121

Publication date

06-2020

Peer reviewed

Yes

Austrian Fields of Science 2012

103014 Nuclear physics

Keywords

Portal url

https://ucris.univie.ac.at/portal/en/publications/pushing-limits-of-icpmsms-for-the-determination-of-ultralow-236uu238-isotope-ratios(421b8820-f834-4c82-9b82-fd29c2a2a499).html