Caracterização da excreção de tório em uma região rica em monazita como subsídio para análise da incorporação em situações de exposição ocupacional e de público
- L.M.Q.C. Julião
- PhD Thesis, UERJ,
Simultaneous determinations of nickel, niobium, uranium and thorium have been performed in biological material as urine and feces utilising the Inductively Coupled Mass Spectrometry (ICP-MS) technique of analysis. Among the spectroscopic methods for multielementar analysis the mass spectrometry is the only technique that can offer easily interpretable spectra, suitable resolution and low detection limits, which allows the determination trace elements in a complex matrix. In this work the chemical procedures used were the direct dilution of urine samples and the dry ashing before wet mineralisation of fecal samples. The principal requests for the analysis performance are the maximum sample dissociation and the production of monovalent ions. The urine samples were diluted 1:20 with HNO3 1N prepared from hyperpure HNO3 and H2O mili Q. The feces were dry ashed at 600C, wet ashed with 10 mL of hyperpure HNO3 and diluted with HNO3 1N. Standard solutions of talium and indium were added in each sample as internal tracers. The interference of calcium in the nickel analysis was determined and subtracted. The detection limits for Ni, Nb, U and Th were respectively 5.44x10 mg/L, 4.86x10 mg/L, 1.95x10 mg/L and 7.41x10 mg/L. The urine samples used for the determination of Ni, Nb, U and Th concentrations were collected from 68 nonoccupationally exposed inhabitants from Rio de Janeiro City, Brazil, of both sexes and in the age range 7-51 years. Background feces samples were from people in the age range of 22-58 years. The results obtained for excretion of Ni are in agreement with the ICRP published values. The values determined for U and Th excretion in urine and feces are in concordance with other obtained values in Brazil using other analytical techniques. The values for Nb excretion in urine and feces are 2 orders of magnitude below those published for the ICRP reference man.