3rd-INCC

Separation of Ra, Ba and Pb for determination of Ra-226 by isotope dilution alpha spectrometry and Pb-210 by liquid scintillation spectrometry

22 Sept 2011, 17:30

1h 30m

Paladini (Città del Mare, Terrasini - Palermo - Sicily - Italy)

poster Radioanalytical Chemistry and Nanoparticles Poster Section 2

Speaker

Dr Gyula Kis-Benedek (International Atomic Energy Agency (IAEA))

Description

The determination of 226Ra and 210Pb is important for characterization of new and existing reference materials, for use as natural tracers in environmental studies and in environmental assessments when natural radionuclides are present at elevated levels. The 226Ra and 210Pb ratio of characterized reference materials changes with time. Due to possible partial escape of 222Rn from the containers, the calculation of radioactive decay and ingrowth is not reliable after some years, therefore the values have to be re-measured from time to time. In addition soil and sediment matrices usually contain Ba around 100-1000 mg kg-1. This barium content of the samples often disturbs the preparation of the Ra alpha sources and restricts the sample size. The method presented here is based on a simple but efficient separation of Pb and Ra from Ba. After the chemical separation 226Ra is determined by isotope dilution alpha spectrometry (typical resolution of226Ra alpha sources is 30-60 keV FWHM) and 210Pb by liquid scintillation spectrometry. The method is selective and sensitive and provides reliable determination of 226Ra and 210Pb in 0.5-2 g of soil and sediment samples with limits of detectable activities of 0.00016 Bq/sample and 0.006 Bq/sample respectively.