Radiometric evaluation of diglycolamide resins for the chromatographic separation of actinium from fission product lanthanides

Publication date: 1 December 2017
Source:Talanta, Volume 175
Author(s): Valery Radchenko, Tara Mastren, Catherine A.L. Meyer, Alexander S. Ivanov, Vyacheslav S. Bryantsev, Roy Copping, David Denton, Jonathan W. Engle, Justin R. Griswold, Karen Murphy, Justin J. Wilson, Allison Owens, Lance Wyant, Eva R. Birnbaum, Jonathan Fitzsimmons, Dmitri Medvedev, Cathy S. Cutler, Leonard F. Mausner, Meiring F. Nortier, Kevin D. John, Saed Mirzadeh, Michael E. Fassbender
Actinium-225 is a potential Targeted Alpha Therapy (TAT) isotope. It can be generated with high energy (≥ 100MeV) proton irradiation of thorium targets. The main challenge in the chemical recovery of ²²⁵Ac lies in the separation from thorium and many fission by-products most importantly radiolanthanides. We recently developed a separation strategy based on a combination of cation exchange and extraction chromatography to isolate and purify ²²⁵Ac. In this study, actinium and lanthanide equilibrium distribution coefficients and column elution behavior for both TODGA (N,N,N′,N′-tetra-n-octyldiglycolamide) and TEHDGA (N,N,N′,N′-tetrakis-2-ethylhexyldiglycolamide) were determined. Density functional theory (DFT) calculations were performed and were in agreement with experimental observations providing the foundation for understanding of the selectivity for Ac and lanthanides on different DGA (diglycolamide) based resins. The results of Gibbs energy (ΔGaq) calculations confirm significantly higher selectivity of DGA based resins for Ln^III over Ac^III in the presence of nitrate. DFT calculations and experimental results reveal that Ac chemistry cannot be predicted from lanthanide behavior under comparable circumstances.

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