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

As the most important plutonium isotopes, 238 Pu, 239 Pu, 240 Pu, and 241 Pu are normally measured 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 measurement of 239 Pu, 240 Pu, and 241 Pu. However, ICP-MS is difficult to measure 238 Pu due to the serious isobaric interference of 238 U. This work reports a rapid analytical method to solve this problem for the simultaneous determination of 238 Pu, 239 Pu, 240 Pu, and 241 Pu using triple-quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS) combined with chemical separation. Chemical separation achieved a high decontamination factor of 2.12 × 10 9 for the most critical interfering element, uranium, by using two sequential TK200 columns. The interferences of 238 U 1 H + and 238 U + were effectively eliminated by using 12 mL/min He-6 mL/min NH 3 as the reaction gases in the octupole collision/reaction cell in ICP-MS/MS. Combined with chemical separation, the overall elimination efficiency of 238 U 1 H + reached 3.6 × 10 17 , which is 10 5 times better than the reported method. With the high 238 U + elimination efficiency of 1.12 × 10 4 in the ICP-MS/MS measurement, the overall removal efficiency of 238 U + reached 10 13 , guaranteeing accurate determination of femtogram-level 238 Pu as well as 239 Pu, 240 Pu, and 241 Pu in the samples containing milligram-level 238 U. The detection time is reduced to minutes, well fulfilling the requirement of rapid analysis. This method is validated by analyzing the standard reference material and the spiked samples.