Abstract
210Pb is a naturally occurring radionuclide, widely distributed on the earth´s surface and can be incorporated by humans through food chain or directly by ingestion or inhalation in situations of occupational or accidental exposures. It concentrates in bone tissue when absorbed, presenting a rather long biological half-life and producing one of the highest skeletal doses among naturally occurring radionuclides under conditions of average background exposure. Because of its metabolic and dosimetric characteristics, 210Pb becomes an important isotope from the radiation protection point of view. This work presents the development of a methodology for the determination of 210Pb by liquid scintillation. It is the modification of a sequential analysis for naturally occurring radionuclides in environmental samples without the need of waiting for secular equilibrium to be achieved with 210Bi. The methodology has shown to be precise, stable and provides consistent results when evaluated according to the criteria established in the Brazilian Intercomparison Program promoted by the IRD.
Highlights
INTRODUCTIONProportional counting presents lower detection limit and the time for the secular equilibrium to be achieved between 210Pb and 210Bi is lowered to 15 days
210Pb is a product of the 238U decay chain for which reliable bioassay techniques are of interest to a wide range of applications in the field of radiation protection since it presents one of the highest committed effective dose coefficients among naturally occurring radionuclides [1].210Pb can be measured directly by gamma-spectrometry [2] or indirectly, through the determination of 210Po by alpha-spectrometry [3] or measuring 210Bi in a proportional counter [4]
Proportional counting presents lower detection limit and the time for the secular equilibrium to be achieved between 210Pb and 210Bi is lowered to 15 days
Summary
Proportional counting presents lower detection limit and the time for the secular equilibrium to be achieved between 210Pb and 210Bi is lowered to 15 days Considering that it is a quantitative analysis and only total count will be taking into account, this technique can be highly affected by unknown interferences possibly present in the sample [4]. This work presents a suspension gel method applied for faster determination of 210Pb by liquid scintillation based on simultaneous radiochemical separation of 226Ra and 210Pb, by direct measurement, without the need to wait for secular equilibrium with 210Bi be achieved. This technique can be applied to any sample, after proper digestion, in liquid form in a HNO3 1% matrix
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