Processing of bone samples for the determination of ultra low-levels of uranium and plutonium

Summary

We have developed cleanroom compatible techniques for processing bone samples for characterization of their uranium and plutonium content. The bone samples are dried and ashed in quartz crucibles placed inside cleanroom compatible thermal ashing furnaces. The bone ash is dissolved in ultra-pure acids prepared by sub-boiling distillation. The uranium and plutonium in the samples are isolated and purified by ion-exchange chromatography and measured by thermal ionization mass spectrometry. The technique is capable of detecting 74 picograms of ²³⁸U and 8 femtograms of ²³⁹Pu in 100 mg bone ash samples. If the ash contains larger amounts of uranium and plutonium, the technique can be used to isotopically fingerprint the material to identify potential origins.