Liquid-scintillation analysis of {sup 222}Rn in water by alpha-beta discrimination

A procedure is described for the assay of {sup 222}Rn in water that reliably distinguishes between alpha and beta radiations. Sample preparation is minimized, background is low, an energy resolution of 6% is possible and conventional 20-mL, liquid-scintillation vials are used. The method was developed using the alpha-beta discrimination feature of the Beckman LS6000 counter. Application of this technology to current liquid-scintillation procedures for {sup 222}Rn in drinking water provides a background of about 0.1 cpm and a detection limit of 20 pCi/L for a 40-minute count on a two-day-old sample or 4 pCi/L for a 1000-minute count. Environmentally-safe cocktails are compatible with the technique.