Rapid and Simultaneous Determination of 238Pu, 239Pu, 240Pu, and 241Pu 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.