Optimization of AlphaGUARD AquaKIT set-up for analysis of radon in water using stainless-steel bottles and its validation through IAEA standard samples

Highlights: • An optimization of ALPHAGUARD-AQUAKIT system has been developed. • Stainless-steel containers as virtually shatterproof bottles for testing radon in water were used. • Method validation was assessed using IAEA proficiency test QC samples with known ²²⁶Ra activity. • Radon activity and the annual effective dose for ingestion was analyzed for the first time in the tap water of the city of Seville (Spain). In this study, a system composed of an ionization chamber AlphaGUARD (PQ 2000), an AquaKIT set and an AlphaPUMP was calibrated to measure ²²²Rn in water. First, the system was checked for leakages using a NIST traceable ²²⁶Ra source. Then, we tested polyethylene terephthalate (PET) and stainless-steel bottles for sample storage estimating radon loss over time. Results showed that stainless-steel was a better suitable material for sample storage. Additionally, system setup was further validated by measuring IAEA reference materials issued within the framework of several interlaboratory intercomparisons. Finally, the procedure was applied to bottled mineral and tap waters collected in Sevilla (Spain) including annual effective dose for ingestion for adults children, and infants.