An improved method for low-level222Rn determination in environmental waters by liquid scintillation counting with pulse shape analysis

A method in which²²²Rn is extracted from 0.5 1 water samples to 20 ml toluene is described. 10 ml toluene solution with extracted²²²Rn is directly added to a glass scintillation vial containing 10 ml of liquid naphthalene based scintillation cocktail. Apart from diluting by toluene, the final counting solution still has excellent properties in terms of: / separation by pulse shape analysis, detection efficiency and background in the -region. The detection limit of²²²Rn for 0.5 1 water samples was 1.5 mBq l^–1 (for 12,000 s count time). The concentration of²²²Rn in different environmental samples such as rain, tap and mineral waters as well as deep well waters were determined.