The use of carbon dioxide as the reaction cell gas for the separation of uranium and plutonium in quadrupole inductively coupled plasma mass spectrometry (ICP-MS) for nuclear forensic samples

The use of carbon dioxide (CO2) as a reaction cell gas for separation and trace analysis of uranium and plutonium by inductively coupled plasma mass spectrometry was investigated. For the analysis of the resultant UO2+ product ion, it was shown that quantitative determination of uranium concentration was achievable within +/- 7% uncertainty for samples containing plutonium. In addition, uranium isotope ratios were measured within +/- 12% for standard reference materials of several enrichments. This was achieved in both nitric acid and digested cellulose filter paper solutions-a common nuclear forensic sample substrate. However, non-linearity and long term signal instability was observed for plutonium at the high flow rate of CO2 and tuning parameters required to minimise uranium interferences. Therefore, plutonium analysis was not achievable.