Rapid and Simultaneous Determination of Pu-238, Pu-239, Pu-240, and Pu-241 in Samples with High-Level Uranium Using ICP-MS/MS and Extraction Chromatography

As the most important plutonium isotopes, Pu-238, Pu-239, Pu-240, and Pu-241 arenormallymeasured by two to three techniques, which are tedious, time-consuming,and not suitable for rapid analysis in emergency situations. Recently,ICP-MS has become a competitive technique for the rapid measurementof Pu-239, Pu-240, and Pu-241. However,ICP-MS is difficult to measure Pu-238 due to the seriousisobaric interference of U-238. This work reports a rapidanalytical method to solve this problem for the simultaneous determinationof Pu-238, Pu-239, Pu-240, and Pu-241 using triple-quadrupole inductively coupled plasma massspectrometry (ICP-MS/MS) combined with chemical separation. Chemicalseparation achieved a high decontamination factor of 2.12 x 10(9) for the most critical interfering element, uranium, by usingtwo sequential TK200 columns. The interferences of (UH+)-U-238-H-1 and U-238(+) were effectivelyeliminated by using 12 mL/min He-6 mL/min NH3 asthe reaction gases in the octupole collision/reaction cell in ICP-MS/MS.Combined with chemical separation, the overall elimination efficiencyof (UH+)-U-238-H-1 reached 3.6 x 10(17), which is 10(5) times better than the reportedmethod. With the high U-238(+) elimination efficiencyof 1.12 x 10(4) in the ICP-MS/MS measurement, the overallremoval efficiency of U-238(+) reached 10(13), guaranteeing accurate determination of femtogram-level Pu-238 as well as Pu-239, Pu-240, and Pu-241 in the samples containing milligram-level U-238. Thedetection time is reduced to minutes, well fulfilling the requirementof rapid analysis. This method is validated by analyzing the standardreference material and the spiked samples.

Automated summary

This study reports a rapid analytical method to simultaneously determine Pu-238, Pu-239, Pu-240, and Pu-241 using triple-quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) combined with chemical separation. The method achieved high decontamination factors for uranium interference and effectively eliminated isobaric interferences. The overall elimination efficiency and removal efficiency of uranium interference were significantly improved compared to reported methods. The detection time was reduced to minutes, satisfying the requirement for rapid analysis.