Validation of a method for measuring 226Ra in drinking waters by LSC

• Liquid scintillation counting (LSC) double-phase technique has been used for 226Ra analysis.
• Teflon coated vials and a water immiscible scintillation cocktail (Ultima Gold F) have been used.
• The method has been validate under ISO 17025 requirements and validation data reported in the paper.
• Repeatability has been evaluated and its contribution has been used in uncertainty calculation.
• The method has been widely applied in measuring drinking water in Italy.

A simple method for measuring 226Ra in drinking waters has been validated and validation parameters are provided. It is based on the measurement by LSC of 222Rn, at equilibrium with 226Ra, which is absorbed into a water immiscible scintillation cocktail (Ultima Gold F) inside the counting vial. The validated application field ranges between the detection limit (2·10−3 Bq/kg) to 150 Bq/kg. The method has proven to be reliable, effective and suitable for wide-range measuring campaigns. A summary of results obtained in recent years is also given.