Multimedia analysis of radon in 10 mL of air for in-laboratory quality assurance

A new, simple, reliable and self-consistent procedure has been developed to produce, handle and measure radon in 10 mL of air in the three media air, water and charcoal simultaneously. Equal and low activities of radon (∼ 200 Bq, ∼ 4 ag) are transferred with a 10 mL gas syringe from a 3.8 L natural, harmless and constant radon source to three receivers: a 48 L Peli case with outdoor air, an 0.5 L bottle with tap water, and a 22 mL tube with activated charcoal. Concentrations, i.e. activities in the three media are measured with different methods providing independent results. Hence, in-laboratory cross-method calibration and traceability to a certified standard is available for radon in air and in water for the first time and with minimum effort. (author)