Analysis of sub-picogram quantities of 238Pu by thermal ionization mass spectrometry

A multiple ion-counting total evaporation technique has been developed for precise analysis of sub-picogram (pg) quantities of 238Pu by thermal ionization mass spectrometry (TIMS). A resin bead loading procedure was tailored to minimize uranium (U) contamination during loading. This loading technique, coupled with a mass spectrometry protocol that minimizes U ionization and removal of bulk U with ion exchange chromatography, allows for single pg-sized aliquots of plutonium (Pu) to be measured without interference from 238U. This technique has the potential to provide complete isotopic characterization of trace amounts of Pu by TIMS, without the need for alpha spectrometry.