Separation of Protactinium Employing Sulfur-Based Extraction Chromatographic Resins

Protactinium-230 (t(1/2) = 17.4 d) is the parent isotope of U-230 (t(1/2) = 20.8 d), a radionuclide of interest for targeted alpha therapy (TAT). Column chromatographic methods have been developed to separate no-carrier-added Pa-230 from proton irradiated thorium targets and accompanying fission products. Results reported within demonstrate the use of novel sulfur bearing chromatographic extraction resins for the selective separation of protactinium. The recovery yield of Pa-230 was 93 +/- 4% employing a R3P=S type commercially available resin and 88 +/- 4% employing a DGTA (diglycothioamide) containing custom synthesized extraction chromatographic resin. The radiochemical purity of the recovered Pa-230 was measured via high purity germanium gamma-ray spectroscopy to be >99.5% with the remaining radioactive contaminant being Nb-95 due to its similar chemistry to protactinium. Measured equilibrium distribution coefficients for protactinium, thorium, uranium, niobium, radium, and actinium on both the R3P=S type and the DGTA resin in hydrochloric acid media are reported, to the best of our knowledge, for the first time.