A sensitive and accurate method for determining ultra low-level 210Pb and 212Pb in water samples through double measurements was developed.Pb was pre-concentrated as hydroxides,separated from alkaline earth elements as PbS precipitate,purified by an anion exchange resin chromatography column,precipitated as PbSO4 for source preparation and counted by a low background β-counter.The procedure was checked with IAEA reference materials,and the results agreed well with the recommended values.Theminimum detectable activity was 0.062 mBq·L-1 for 210Pb and 0.053 mBq·L-1 for 212Pb with a 48 L water sample.Seventeen drinking water samples were analyzed,with a Pb recovery of 88.8?5.5%,and the typical activity concentrations were 0.191?15.1 mBq·L-1 for 210Pb and of 1.12?5.77 mBq·L-1 for 212Pb.The estimated committed effective doses to adult members of the public in Italy due to intake of 210Pb and 212Pb in drinking water were 0.096?7.59 μSv·a-1 and 0.005?0.025 μSv·a-1,respectively.
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