title: Determining picogram quantities of U in human urine by thermal ionization mass spectrometry.
abstract: The U concentration in Standard Reference Material 2670 (Toxic Metals in Freeze-Dried Urine) and the urine of two preschool-age children were determined by measuring the chemically separated U by isotope dilution thermal ionization mass spectrometry using ion counting detection. This procedure can detect about 1% of the U atoms loaded into the mass spectrometer and has a total chemical blank of about 5 pg U. The U concentration in SRM 2670 was found to be 113 +/- 2 pg 238U/ml (1 s). At this concentration, a 1-ml sample is sufficient for a determination with a total uncertainty of less than 5%. The U concentrations in the two children were 3.1 +/- 0.9 and 3.6 +/- 0.9 pg 238U/g. These values suggest that the U concentration in urine of unexposed persons may be at this low level or lower.
mesh_terms: D002675:Child, Preschool; D006801:Humans; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008433:Mathematics; D008832:Microchemistry; D012015:Reference Standards; D014501:Uranium / Q000652:urine*
chemical_list: D014501:Uranium