Solvent extraction method for determination of plutonium in soft tissue

A simple, quick, and accurate method has been developed for the determination of plutonium isotopes in soft tissues. First 242Pu tracer is added and then the tissues are digested using concentrated nitric acid followed by a mixture of nitric and sulfuric acids. Plutonium is then coprecipitated with iron carrier after the addition of ammonium hydroxide. The precipitate is dissolved in HNO3 (1 : 1) after complete removal of sulfate ions and the acidity adjusted to 3 M. Plutonium is maintained in the +4 valence state and extracted twice with 25 percent trilaurylamine in xylene (pre-equilibrated with 3M nitric acid). The organic phase is washed twice with equal volumes in 10 M HCl to remove traces of thorium and then with HNO3 to remove iron and uranium. Plutonium is then scrubbed from the trilaurylamine phase two times with 2 M H2SO4, evaporated almost to dryness, electrodeposited onto a platinum planchet, and counted by alpha spectrometry with a surface barrier silicon diode. The final recovery ranged from 49 to 85 percent with a mean of 61 percent