Isotope Production Laboratory, Collider-Accelerator Division, Brookhaven National Laboratory, Upton, NY 11973, USA.
Department of Biology, Chemistry, and Geoscience, Fairmont State University, Fairmont, WV 26554, USA.
Molecules. 2019 May 18;24(10):1921. doi: 10.3390/molecules24101921.
Actinium-225 (Ac) 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 Ac. The following variables were tested: pH of load solution (1.5-4.6); rinse steps with various concentrations of HCl, HNO, HSO, and combinations of HCl and HNO; various thorium chelators to block retention; MP50 and AG50 resins; and retention of 20-45 elements with different rinse sequences. The research indicated that HCl removes more isotopes earlier than HNO, but that some elements, such as barium and radium, could be eluted with ≥2.5 M HNO. The optimal pH of the load solution was 1.5-2.0, 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 HNO, 6 BV of 2.5 M HNO and 20 BV of 6 M HNO. The sequence recovered >90% of Ac with minimal Ra and thorium present.
锕-225（Ac）可以通过质子辐照钍（Th）靶来用直线加速器产生，但 Th 也会发生裂变并产生 400 多种其他放射性同位素。目前还没有关于优化阳离子步骤进行纯化的研究。本文研究了优化用于纯化 Ac 的阳离子交换步骤。测试了以下变量：负载溶液的 pH 值（1.5-4.6）；用不同浓度的 HCl、HNO、HSO 以及 HCl 和 HNO 的组合进行的冲洗步骤；各种用于阻止保留的钍螯合剂；MP50 和 AG50 树脂；以及不同冲洗顺序对 20-45 种元素的保留。研究表明，HCl 比 HNO 更早地去除更多的同位素，但某些元素，如钡和镭，可能可以用≥2.5 M HNO 洗脱。负载溶液的最佳 pH 值为 1.5-2.0，优化的冲洗序列为 5 个床体积（BV）的 1 M 柠檬酸 pH 2.0、3 BV 的水、3 BV 的 2 M HNO、6 BV 的 2.5 M HNO 和 20 BV 的 6 M HNO。该序列以最小的 Ra 和钍存在回收了>90%的 Ac。
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