Expósito-Suárez Víctor Manuel, Suárez-Navarro José Antonio, Benavente José Francisco
Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Avenida Complutense 40, 28040 Madrid, Spain.
Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Plaza de las Ciencias, 2, Moncloa-Aravaca, 28040 Madrid, Spain.
Molecules. 2024 Sep 5;29(17):4225. doi: 10.3390/molecules29174225.
Thorium is a radionuclide used in various environmental studies such as dating, sediment movement, soil-plant transfer studies, and contamination of waste from the natural fuel cycle. The liquid-liquid extraction method using tri-n-butyl phosphate (TBP) allows for the separation of Th from the accompanying actinides. However, the separation of Th and U present in the same sample is not trivial. This separation is influenced by the starting acid (HCl or HNO), the concentration of TBP in an organic solvent, and the concentration of the acid used for re-extracting Th, which is typically HCl. Therefore, it is necessary to study these factors to ensure that the method has sufficient chemical yield and selectivity in complex matrices. This study presents a systematic investigation of the aforementioned parameters, making the necessary variations to select an optimal method for the radiochemical separation of Th. The ideal conditions were obtained using 4 M HCl as the acid prior to extraction, a 1:4 solution of TBP in xylene, and 4 M HCl as the re-extracting agent. The accuracy and precision were studied in four intercomparison exercises conducted in quadruplicate, using the parameters E, RB(%), and RSD(%) for Th and Th. The sensitivity of the method was experimentally studied and the limit of detection (LoD) was determined according to ISO 11929:2005. Additionally, the linearity of the method showed that the experimental and theoretical activity concentrations of Th and Th had slopes of 1 with an intercept close to 0.
钍是一种放射性核素，用于各种环境研究，如年代测定、沉积物移动、土壤-植物转移研究以及天然燃料循环产生的废物污染研究。使用磷酸三丁酯（TBP）的液-液萃取方法可实现钍与伴生锕系元素的分离。然而，分离同一样品中存在的钍和铀并非易事。这种分离受起始酸（HCl或HNO）、有机溶剂中TBP的浓度以及用于反萃取钍的酸（通常为HCl）的浓度影响。因此，有必要研究这些因素，以确保该方法在复杂基质中具有足够的化学产率和选择性。本研究对上述参数进行了系统研究，通过进行必要的变量调整来选择钍放射化学分离的最佳方法。萃取前使用4 M HCl作为酸、TBP与二甲苯的1:4溶液以及4 M HCl作为反萃取剂可获得理想条件。在四次重复进行的四项比对实验中，使用钍和钍的E、RB(%)和RSD(%)参数研究了准确性和精密度。通过实验研究了该方法的灵敏度，并根据ISO 11929:2005确定了检测限（LoD）。此外，该方法的线性表明，钍和钍的实验活性浓度与理论活性浓度的斜率为1，截距接近0。
