title: Flow-injection technique for determination of uranium and thorium isotopes in urine by inductively coupled plasma mass spectrometry.
abstract: A sensitive and efficient flow-injection (FI) preconcentration and matrix-separation technique coupled to sector field ICP-mass spectrometry (SF-ICP-MS) has been developed and validated for simultaneous determination of ultra-low levels of uranium (U) and thorium (Th) in human urine. The method is based on selective retention of U and Th from a urine matrix, after microwave digestion, on an extraction chromatographic TRU resin, as an alternative to U/TEVA resin, and their subsequent elution with ammonium oxalate. Using a 10 mL sample, the limits of detection achieved for 238U and 232Th were 0.02 and 0.03 ng L(-1), respectively. The accuracy of the method was checked by spike-recovery measurements. Levels of U and Th in human urine were found to be in the ranges 1.86-5.50 and 0.176-2.35 ng L(-1), respectively, well in agreement with levels considered normal for non-occupationally exposed persons. The precision obtained for five replicate measurements of a urine sample was 2 and 3% for U and Th, respectively. The method also enables on-line measurements of the 235U/238U isotope ratios in urine. Precision of 0.82-1.04% (RSD) was obtained for 235U/238U at low ng L(-1) levels, using the FI transient signal approach.
authors.affiliation: Environmental Resources Studies, Trent University, 1600 West Bank Drive, Peterborough, Ontario, K9J 7B8, Canada. karima_benkhedda@hc-sc.gc.ca
authors.forename: Karima
authors.initials: K
authors.lastname: Benkhedda
authors.forename: Vladimir N
authors.initials: VN
authors.lastname: Epov
authors.forename: R Douglas
authors.initials: RD
authors.lastname: Evans
mesh_terms: D017022:Flow Injection Analysis / Q000379:methods; D006801:Humans; D007554:Isotopes / Q000652:urine; D013058:Mass Spectrometry / Q000379:methods*; D013910:Thorium / Q000652:urine*; D014501:Uranium / Q000652:urine*
chemical_list: D007554:Isotopes; D014501:Uranium; D013910:Thorium