Inductively coupled plasma mass spectrometry (ICP-MS), coupled with a large-bore direct injection high efficiency nebulizer (LB-DIHEN), was utilized to determine the concentration and isotopic ratio of uranium in 11 samples of synthetic urine spiked with varying concentrations and ratios
of uranium isotopes. Total U concentrations and 235U/238U isotopic ratios ranged from 0.1 to 10 μg/L and 0.0011 and 0.00725, respectively. The results are compared with data from other laboratories that used either α-spectrometry or quadrupole-based ICP-MS with a conventional
nebulizer–spray chamber arrangement. Severe matrix effects due to the high total dissolved solid content of the samples resulted in a 60 to 80% loss of signal intensity, but were compensated for by using 233U as an internal standard. Accurate results were obtained with LB-DIHEN–ICP-MS,
allowing for the positive identification of depleted uranium based on the 235U/238U ratio. Precision for the 235U/238U ratio is typically better than 5% and 15% for ICP-MS and α-spectrometry, respectively, determined over the concentrations
and ratios investigated in this study, with the LB-DIHEN–ICP-MS system providing the most accurate results. Short-term precision (6 min) for the individual 235U and 238U isotopes in synthetic urine is better than 2% (N = 7), compared to ~5% for conventional
nebulizer–spray chamber arrangements and >10% for α-spectrometry. The significance of these measurements is discussed for uranium exposure assessment of Persian Gulf War veterans affected by depleted uranium ammunitions.
Department of Chemistry, The George Washington University, Washington, D.C. 20052 2:
Armed Forces Radiobiology Research Institute, Bethesda, Maryland 20889
Publication date: September 1, 2004
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