Accelerator mass spectrometry of 90Sr in environmental samples utilizing laser photo-detachment

Abstract

trontium-90 (90Sr, 28.9 years) is a key fission product nuclide in internal dose assessment because it accumulates in bones and teeth in the body, causing health problems. Therefore, it is essential to know the distribution of 90Sr in the environment and its temporal variation (90Sr enrichment in biota), which requires efficient analysis of many environmental samples. The sensitive analysis of 90Sr with accelerator mass spectrometry (AMS) was developed in this study. In this study, the validity of the AMS method was demonstrated by analyzing environmental samples with known 90Sr concentrations (IAEA-447, IAEA-A-12, and IAEA-TEL-2015-03 sample 5: 1 dry-g each). The chemical separation developed in this study takes approximately two days and is a more straightforward procedure than conventional β-ray detection methods. The 90Sr measurements were conducted on the AMS system combined with the Ion Laser InterAction Mass Spectrometry (ILIAMS) system. The AMS method achieved a limit of detection <0.1 mBq (<1.3×105 atoms) for 90Sr, which is 1/30 of typical β-ray detection. As a result of the lower detection limit, the AMS method allows 90Sr quantification with smaller sample volumes. For example, a Japanese freshwater sample with a 90Sr concentration of 4 mBq/L requires a sample volume of 5 liters.