Feasibility study of a screening method for plutonium in urine by Q-ICP-MS

[摘要] The monitoring of personnel for exposure to radioactive elements is a regulatoryrequirement for any nuclear installation and due to the nature of the research, the needfor a non-invasive procedure for the monitoring for exposure to plutonium has beenidentified at the South African Nuclear Energy Corporation (NECSA). Historically,analyses of short-lived radioactive elements were performed by α-spectrometry. Butdue to the well documented drawbacks of the older generation of α-spectrometeranalysis, Quadrupole Inductively Coupled Mass Spectrometry (Q-ICP-MS) wassuggested as an alternative technique.A feasibility study was undertaken to determine whether sub-trace concentrations ofplutonium in urine can be determined using a modern, standard Q-ICP-MS. Asimplified One Variable at a Time (OVAT) approach was used to establish optimalanalytical conditions starting from instrument setup and ending in samplepreparation.The optimum sample preparation determined required 50 mL urine which underwentco-precipitation, wet-ashing and solid phase extraction using Tetra Valent Actinide(TEVA)-resin. Calibration standards ranged from 5 to 100 pg L-1 and the optimisedmethod produced LOD’s of 0.2 pg L-1 and LOQ’s of 0.5 pg L-1. Sample intra-assayprecision at 0.5- and 15 pg L-1 were 11.3% and 4.43% respectively, in the urinematrix. The bias was 8% and 0% at the same concentrations. The method wasevaluated using samples from an international proficiency study and two out of thethree tests that could be quantified passed specification. According to ISO 13528 amethod is acceptable if two out of three tests pass.The method has been verified and a modern, standard Q-ICP-MS has been proven tobe a suitable alternative to α-spectrometry with respect to sub-trace plutoniumanalysis.

[发布机构] University of the Witwatersrand