Determination of micro amounts of lead with ThB (Pb212) as a tracer by the “Isotope Dilution Method of Analysis” has been studied.
ThB can be easily obtained from ordinarly chemical reagent of thorium nitrate by extracting with dithizone. If dithizone in chloroform solution is saturated with lead containing radioactive tracer ThB, and equilibrium is established with the aqueous layer containing varying amounts of lead, the amounts of lead in the aqueous solution can be easily found by simply measuring the activities in the organic layer from the following relation:
With this relation, the determination of micro amounts of lead in aqueous solutions can be easily made without any auxiliarly chemical methods.