Chelator-impregnated resins have been studied earlier for the chemical separation of elements in aqueous solutions, but issues with their chemical stability have limited their use in the separation of (medical) radionuclides from their respective irradiated targets. We developed a polydimethylsiloxane (PDMS)-based chelator-impregnated resin that showed a high chemical stability against leaching. Several different chelators were tested in this study. After impregnation of the PDMS beads with the di-2-ethylhexylphosphoric acid (D2EHPA) chelator, an in-flow separation study with various radionuclides (Y-90, La-140, and Ac-225) was conducted. These three radionuclides have potential use in nuclear medicine and a production route through irradiation of Sr-, Ba-, and Ra-targets respectively, necessitating their chemical separation. The D2EHPA-impregnated beads achieved high adsorption efficiencies of 99.89% ± 0.14%, 99.50% ± 0.10%, and 98.51% ± 0.25%, for Y-90, La-140, and Ac-225, respectively, while co-adsorption of minor amounts (< 3%) of the targets were reported. These results, together with the high chemical stability of the PDMS-based resin, highlight the potential of chelator-impregnated resins in the rapidly growing field of (medical) radionuclide production.@en

Background: The radionuclide Ga-68 is commonly used in nuclear medicine, specifically in positron emission tomography (PET). Recently, the interest in producing Ga-68 by cyclotron irradiation of [⁶⁸Zn]Zn nitrate liquid targets is increasing. However, current purification methods of Ga-68 from the target solution consist of multi-step procedures, thus, leading to a significant loss of activity through natural decay. Additionally, several processing steps are needed to recycle the costly, enriched target material. Results: To eventually allow switching from batch to continuous production, conventional batch extraction and membrane-based microfluidic extraction were compared. In both approaches, Ga-68 was extracted using N-benzoyl-N-phenylhydroxylamine in chloroform as the organic extracting phase. Extraction efficiencies of up to 99.5% ± 0.6% were achieved within 10 min, using the batch approach. Back-extraction of Ga-68 into 2 M HCl was accomplished within 1 min with efficiencies of up to 94.5% ± 0.6%. Membrane-based microfluidic extraction achieved 99.2% ± 0.3% extraction efficiency and 95.8% ± 0.8% back-extraction efficiency into 6 M HCl. When executed on a solution irradiated with a 13 MeV cyclotron at TRIUMF, Canada, comparable efficiencies of 97.0% ± 0.4% were achieved. Zn contamination in the back-extracted Ga-68 solution was found to be below 3 ppm. Conclusions: Microfluidic solvent extraction is a promising method in the production of Ga-68 achieving high efficiencies in a short amount of time, potentially allowing for direct target recycling. Graphical Abstract: [Figure not available: see fulltext.].

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