UC Irvine

To achieve industrial scale separation of long lived isotopes from spent nuclear fuel requires more work on the advanced chemistry involved. Analytical methods are important in gaining information that can support a more complete and thorough understanding of solvent extraction in spent nuclear fuel. Electrospray Ionization Mass Spectroscopy (ESI-MS) is a method used to determine masses of compounds in liquid samples. There is little understanding of how ESI-MS can be applied to analyzing compounds when extraction experiments are performed. In this work, extractions were done on Nd with di-(2-ethyl hexyl) phosphoric acid (HDEHP) and on Dy, La, Lu, Yb with varying amounts of tri-n-butyl phosphate (TBP) and/or dibutyl phosphate (HDBP). After extractions the organic phases were diluted 100 times in acetonitrile and the ESI-MS spectra were generated. There were five large peaks (and numerous less pronounced peaks) in the TBP/HDBP system that were distinguished by their isotopic spread and varied by the mass difference between the metals that were extracted. These five peaks were consistent for all metals tested. The results also showed that there is replicability in the experiments, and that species existing in solution may possibly be determined by their masses in ESI-MS spectra. Though comprehensive species identification has not been achieved at this point, this evidence shows ESI-MS may be a useful tool in determining some of the more common liquid phase extraction complexes.