Volume 37, Number C1, February 2002ECORAD 2001: The Radioecology - Ecotoxicology of Continental and Estuatine Environments
|Page(s)||C1-957 - C1-962|
|Published online||25 March 2010|
A new method for determination of uranium isotopes in water, vegetation and soil by alpha spectrometry
National Environmental Protection Agency, Via V. Brancati 48, 00144 Roma, Italy
A new and accurate method for determination of uranium isotopes (238U, 234U and 235U) in environmental samples by alpha spectrometry has been developed. Uranium is preconcentrated from filtered water samples by coprecipitation with iron (III) hydroxide at pH 9-10 using ammonia solution and the precipitate is dissolved with HNO3 and mineralised with H2O2 and HF; uranium in biological samples is ashed at 600 °C, leached out with Na2CO3 solution and mineralised with HNO3, HF and H2O2; uranium in soil samples is melted with Na2CO3 and Na2O2 at 600 °C and leached out with HCl, HNO3 and HF. The mineralised or leaching solution in 2 M HNO3 is passed through a Microthene-TOPO (trioctyl- phosphine oxide) column; after washing uranium is directly eluted into a cell with ammonium oxalate solution, electrodeposited on a stainless steel disk and measured by alpha spectrometry. The lower limits of detection of the method are 0.37 Bq kg-1 (soil) and 0.22 mBq l-1 (water) for 238U and 234U and 0.038 Bq kg-1 (soil) and 0.022 mBq l-1 (water) for 235U if 0.5 g of soil and 1 litre of water are analysed. Five reference materials supplied by IAEA have been analysed and reliable results are obtained. The average uranium yields for waters, mosses, lichens and sediments are 74.5±9.0%, 80.5±8.3%, 77.8±4.9% and 89.4±9.7% respectively.
© EDP Sciences, 2002
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