Determination of Trace Level 241Pu and 241Am in Soil Reference Materials by Mass-shift ICP-MS/MS with UTEVA-DGA Chromatographic Separation

Triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) has been widely used for the measurement of trace level radioactive nuclides, but it is severely limited by interferences from isobaric and polyatomic ions.Specifically, the analysis of 241 Pu and 241 Am is significantly hindered by interferences from Bi, Hf, Pt, Pb, Hg, and Tl, especially in the presence of Cl -, as well as from the radioactive nuclides themselves.This study demonstrates that high-precision analysis of 241 Pu and 241 Am with minimal interferences can be achieved by combining ICP-MS/MS mass-shift mode with chemical separation using UTEVA-DGA chromatographic resin.For the ICP-MS/MS measurement in the mass-shift mode with O2 and He as the reaction and collision gas, respectively, the detection limits of 241 Pu and 241 Am were 0.058 fg/g and 0.017 fg/g, respectively significantly lower than those of other types of ICP-MS.Moreover, polyatomic ion interferences generated by Bi, Hf, Pt, Pb, Hg, and Tl can be eliminated.The established analytical method was successfully validated using two soil standard reference materials (IAEA-375 and IAEA-Soil-6).