Determination of depleted uranium in urine via isotope ratio measurements using large-bore direct injection high efficiency nebulizer-inductively coupled plasma mass spectrometry.

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 (235)U/(238)U isotopic ratios ranged from 0.1 to 10 microg/L and 0.0011 and 0.00725, respectively. The results are compared with data from other laboratories that used either alpha-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 (233)U as an internal standard. Accurate results were obtained with LB-DIHEN-ICP-MS, allowing for the positive identification of depleted uranium based on the (235)U/(238)U ratio. Precision for the (235)U/(238)U ratio is typically better than 5% and 15% for ICP-MS and alpha-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 (235)U and (238)U isotopes in synthetic urine is better than 2% (N = 7), compared to approximately 5% for conventional nebulizer-spray chamber arrangements and >10% for alpha-spectrometry. The significance of these measurements is discussed for uranium exposure assessment of Persian Gulf War veterans affected by depleted uranium ammunitions.

Volatile organic compounds produced during irradiation of mail.

In 2001, Bacillus anthracis spores were delivered through the United States postal system in a series of bioterrorist acts. Controls proposed for this threat included sanitization with high-energy electrons. Solid phase microextraction was used with gas chromatography/mass spectrometry for field sampling and analysis of volatile compounds apparently produced from polymeric materials such as cellulose and plastics, immediately following processing of mail at a commercial irradiation facility. Solid phase microextraction and direct sampling of air into a cryogenically cooled temperature programmable inlet were used in the laboratory for gas chromatography/mass spectrometry analysis of air in contact with irradiated mail, envelopes only (packaged identically to mail), and air inside irradiated plastic mail packaging bags (with neither mail nor envelopes). Irradiated mail or envelope systems produced hydrocarbons such as propane, butane, pentane, hexane, heptane, methylpentanes, and benzene; and oxygen-containing compounds such as acetaldehyde, acrolein, propionaldehyde, furan, 2-methylfuran, methanol, acetone, 2-butanone, and ethanol. In addition to hydrocarbons, methyl and ethyl nitrate were detected in irradiated bags that contained only air, suggesting reactive nitrogen species formed from air irradiation reacted with hydroxy-containing compounds to give nitro esters. The similarities of volatile compounds in irradiated systems containing paper to those observed by researchers studying cellulose pyrolysis suggests common depolymerization and degradation mechanisms in each case. These similarities should guide additional work to examine irradiated mail for chemical compounds not detectable by methods used here.