{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,23]],"date-time":"2026-07-23T11:02:09Z","timestamp":1784804529341,"version":"3.55.0"},"reference-count":24,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2019,5,18]],"date-time":"2019-05-18T00:00:00Z","timestamp":1558137600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000015","name":"U.S. Department of Energy","doi-asserted-by":"publisher","award":["Core funding"],"award-info":[{"award-number":["Core funding"]}],"id":[{"id":"10.13039\/100000015","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100000015","name":"U.S. Department of Energy","doi-asserted-by":"publisher","award":["Workforce development"],"award-info":[{"award-number":["Workforce development"]}],"id":[{"id":"10.13039\/100000015","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Actinium-225 (225Ac) can be produced with a linear accelerator by proton irradiation of a thorium (Th) target, but the Th also underdoes fission and produces 400 other radioisotopes. No research exists on optimization of the cation step for the purification. The research herein examines the optimization of the cation exchange step for the purification of 225Ac. The following variables were tested: pH of load solution (1.5\u20134.6); rinse steps with various concentrations of HCl, HNO3, H2SO4, and combinations of HCl and HNO3; various thorium chelators to block retention; MP50 and AG50 resins; and retention of 20\u201345 elements with different rinse sequences. The research indicated that HCl removes more isotopes earlier than HNO3, but that some elements, such as barium and radium, could be eluted with \u22652.5 M HNO3. The optimal pH of the load solution was 1.5\u20132.0, and the optimized rinse sequence was five bed volumes (BV) of 1 M citric acid pH 2.0, 3 BV of water, 3 BV of 2 M HNO3, 6 BV of 2.5 M HNO3 and 20 BV of 6 M HNO3. The sequence recovered &gt;90% of 225Ac with minimal 223Ra and thorium present.<\/jats:p>","DOI":"10.3390\/molecules24101921","type":"journal-article","created":{"date-parts":[[2019,5,20]],"date-time":"2019-05-20T11:05:07Z","timestamp":1558350307000},"page":"1921","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Optimization of Cation Exchange for the Separation of Actinium-225 from Radioactive Thorium, Radium-223 and Other Metals"],"prefix":"10.3390","volume":"24","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-9892-1534","authenticated-orcid":false,"given":"Jonathan","family":"Fitzsimmons","sequence":"first","affiliation":[{"name":"Isotope Production Laboratory, Collider-Accelerator Division, Brookhaven National Laboratory, Upton, NY 11973, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0570-769X","authenticated-orcid":false,"given":"Bryan","family":"Foley","sequence":"additional","affiliation":[{"name":"Department of Biology, Chemistry, and Geoscience, Fairmont State University, Fairmont, WV 26554, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bryna","family":"Torre","sequence":"additional","affiliation":[{"name":"Department of Chemistry, University at Buffalo, the State University of New York, Buffalo, NY 14260, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Megan","family":"Wilken","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Elizabeth City State University, Elizabeth City, NC 27909, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Cathy S.","family":"Cutler","sequence":"additional","affiliation":[{"name":"Isotope Production Laboratory, Collider-Accelerator Division, Brookhaven National Laboratory, Upton, NY 11973, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Leonard","family":"Mausner","sequence":"additional","affiliation":[{"name":"Isotope Production Laboratory, Collider-Accelerator Division, Brookhaven National Laboratory, Upton, NY 11973, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dmitri","family":"Medvedev","sequence":"additional","affiliation":[{"name":"Isotope Production Laboratory, Collider-Accelerator Division, Brookhaven National Laboratory, Upton, NY 11973, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,5,18]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"147","DOI":"10.1002\/jlcr.1143","article-title":"Synthesis and Evaluation of a water-soluble polymer to reduce Ac-225 daughter migration","volume":"50","author":"Fitzsimmons","year":"2007","journal-title":"J. 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