Determination of natural and depleted uranium in urine at the PPT level: An interlaboratory analytical exercise

An analytical exercise was initiated in order to determine those procedures with the capability to measure total uranium and uranium (U-238/U-235) isotopic ratios in urine samples containing > 0.02 mu g U kg(-1) urine. A host laboratory prepared six identical sets of twelve synthetic urine samples containing total uranium in the range of 25 to 770 ng U kg(-1) urine and with U-238/U-235 isotopic ratios ranging from 138 (100% NU) to 215 (51% DU). Sets of samples were shipped to five testing laboratories (four based in Canada and one based in Europe). Each laboratory utilized one of the following analytical techniques: sector field inductively coupled plasma mass spectrometry (ICP-SF-MS), quadrupole inductively coupled plasma mass spectrometry (ICP-Q-MS), thermal ionization mass spectrometry (TIMS), and instrumental/delayed neutron activation analysis (I/DNAA), in their analyses.