Improving the separation of strontium and barium with Sr Resin using chelating eluent solutions

Abstract

Age dating radioactive 137Cs and 90Sr sources, which are a potential concern in radiation dispersal devices, can provide evidence for attribution in a nuclear forensic investigation. Precise measurement of the 137Cs–137Ba or 90Sr–90Zr isotope ratio by ICP-MS in tandem with non-linearity and mass-bias data manipulation dramatically increases precision and decreases uncertainty, leaving inadequate chemical separation efficiencies as a major contributor—and in some cases the lead contributor—to uncertainty in age determination. To improve the separation of these isobars before ICP-MS analysis, we evaluated eluents containing EDTA and DTPA chelating agents against previously studied eluents for their ability to achieve complete removal of Sr and Ba from Eichrom Technologies’ Sr Resin. Barium separation efficiencies using 0.05 M EDTA, pH-adjusted 0.05 M EDTA, and pH-adjusted 0.05 M DTPA were found to be 100.9 ± 2.2%, 99.4 ± 0.8%, and 99.3 ± 1.2%, respectively. Strontium separation efficiencies using 0.05 M disodium EDTA and 0.05 M potassium EDTA were determined to be 100.14 ± 0.53% and 100.19 ± 0.97% respectively. These results demonstrate that eluents containing chelating agents out-perform previously studied eluent solutions at removing barium and strontium from Sr Resin.