Ultratrace Uranium Fingerprinting with Isotope Selective Laser Ionization Spectrometry
Uranium isotope ratios can provide source information for tracking uranium contamination in a variety of fields, ranging from occupational bioassay to monitoring aftereffects of nuclear accidents. We describe the development of Isotope Selective Laser Ionization Spectrometry (ISLIS) for ultratrace measurement of the minor isotopes 234U, 235U, and 236U with respect to 238U. Optical isotopic selectivity in three-step excitation with single-mode continuous wave lasers is capable of measuring the minor isotopes at relative abundances below 1 ppm, and is not limited by isobaric interferences such as 235UH+ during measurement of 236U. This relative abundance limit approaches the threshold for measurement of uranium minor isotopes with conventional mass spectrometry, typically 10-7, but without mass spectrometric analysis of the laser-created ions. Uranyl nitrate standards from an international blind comparison were used to test analytical performance for different isotopic compositions and with quantities ranging from 11 ng to 10 µg total uranium. Isotopic ratio determination was demonstrated over a linear dynamic range of 7 orders of magnitude with a few percent relative precision and detection limits below 500 fg for the minor isotopes.
- Research Organization:
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 949126
- Report Number(s):
- PNNL-SA-58852; TRN: US0901729
- Journal Information:
- Analytical Chemistry, 80(15):6029-6033, Vol. 80, Issue 15
- Country of Publication:
- United States
- Language:
- English
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