A preliminary study of rapid measurements of aqueous 210Po by accelerator mass spectrometry
Polonium-210 (210Po) is a toxic radioisotope naturally present in freshwater and groundwater that threatens the safety of drinking water supply. Designed for rapid analyses, a new procedure was tested for measuring aqueous 210Po by accelerator mass spectrometry (AMS). Since the longer-lived polonium isotopes 208Po and 209Po suffer from atomic isobaric interferences, we normalized the 210Po ion beam to a beam of 197Au as the reference isotope. 210Po and 197Au solutions were co-precipitated with Ag+ and S2− to form the stable compound Ag2S. This method homogeneously precipitated these two isotopes of different elements and provided good electrical and thermal conductivity when the dried solid was pressed into a target for use in a Cs+ sputter ion source. Beams of atomic Po− were charge changed, and the Po3+ ion was used for subsequent mass and energy analysis. Ion beams of ≥0.20 counts per second per femtogram of 210Po in a target were produced. The measured and prepared 210Po/197Au ratios showed a good linear response when the quantity of 210Po was prepared in a dilution series. With a counting time of less than 1.5 hours per target, the procedure indicated a 210Po detection limit of 20 mBq (0.12 fg), supporting the next phase of development with environmental aqueous samples.