Abstract
The measurement of uranium (U) isotope ratios in urine provides valuable information about the source of U exposure in humans and can be vitally important in a radiological emergency. This method provides rapid and accurate results for 235U/238U at 235U concentrations as low as 0.42 ng/L, which is equivalent to ~200 ng/L of total U for a depleted U (DU) at a 235U/238U ratio of ~0.002. The results are within 6% of Certified Reference Materials target values and agree with Department of Defense Armed Forces Institute of Pathology inter-laboratory comparison target values with a bias range of -6.9% to 7.6%.