The determination of 210Po in urine

To measure 210Po present in normal human urine a technique was developed in which a 4.5 x 11cm silver foil was shaken at room temperature for 48-hr periods in each of two successive volumes of 1.7 l. of urine acidified to 0.5N with HCl. Alpha rays were counted with an ionization chamber, coupled to a vibrating reed electrometer, and capable of measuring α-ray pulses originating on both sides of the silver foil serving as a central electrode. The background α-count was less than 2/hr. Analyses of human urine spiked with 0.29 to 0.58pCi of 210Po, together with studies of urine from dogs carrying significant body burdens of 210Pb, indicated that the average recovery of added 210Po from 1.7 l. volumes of spiked human urine was 72%. If it is assumed that the same percentage of 210Po is extracted from non-spiked urine, then the average 210Po concentration found in 13 analyses of 2 x 1.7 l. samples from 26 different pools of fresh human urine was 0.023pCi/l. Substantial additional 210Po was generated on short aging of the urine through radioactive decay of excreted 210Bi. (author)