Gamma emitting radiotracers 224Ra, 212Pb and 212Bi from natural thorium

A simple method is described for the separation of the title radiotracers from natural thorium in a two-step procedure. 224Ra (ca. 0.15 MBq per batch) slightly contaminated with 228Ra was repeatedly back-extracted from HDEHP heptane solution containing 40 g of thorium by 0.1 M HNO3 and, if necessary, purified by ion exchange. A small cation exchange column loaded with the radium serves as a generator of 212Pb and 212Bi radiotracers of high radionuclide purity, obtained with a nearly quantitative yield.