Chemical Sciences Division, Oak Ridge National Laboratory, USA; Chemistry Department, University of Missouri, Columbia, USA.
Nuclear Nonproliferation Division, Oak Ridge National Laboratory, USA.
Anal Chim Acta. 2022 May 29;1209:339836. doi: 10.1016/j.aca.2022.339836. Epub 2022 Apr 23.
Direct isotope ratio analysis of solid uranium particulates on cotton swipes was achieved using a solution-based microextraction technique, coupled to a quadrupole inductively coupled plasma - mass spectrometer (ICP-MS). This microextraction-ICP-MS methodology provides rapid isotopic analysis which could be applicable to nuclear safeguards measurements. Particulates of uranyl nitrate hexahydrate (UO(NO)·6HO) and uranyl fluoride (UOF) ranging from 6 μm to 40 μm in length were transferred to cotton swipes with a particle manipulator. The microextraction probe then delivers a 5% nitric acid (HNO) solvent onto the swipe surface to extract the uranium species. The extracted sample is then delivered to the ICP-MS for isotopic determination. The majority of uranium signal (∼99% and ∼94% for UO(NO)·6HO and UOF, respectively) was detected in the first 15 s extraction, while subsequent extractions on the same location had low or no U signal, suggesting near complete removal of the solid uranium compounds from the swipe surface. Ten samples (for each of the uranium compounds), were analyzed for their isotopic composition. For UO(NO)·6HO, the determined isotope ratios resulted in a % relative difference (% RD) from the referenced isotope ratios of 0.97, 1.0, and 7.3% for U/U, U/U, and U/U, respectively. The % RD of the UOF isotope ratios were 1.9 and 0.60% for U/U and U/U, respectively. The preliminary limits of detection were determined to be 0.002, 0.4, and 60 pg for U, U and U, respectively This work demonstrates that microextraction ICP-MS is a rapid and sensitive method that could directly determine uranium isotope ratios of UO(NO)·6HO and UOF particulates on cotton swipes.
采用基于溶液的微萃取技术，结合四极电感耦合等离子体质谱仪（ICP-MS），实现了固体铀颗粒在棉签上的直接同位素比分析。该微萃取-ICP-MS 方法提供了快速的同位素分析，可应用于核保障测量。长度为 6 μm 至 40 μm 的六水合硝酸铀酰（UO（NO）·6HO）和氟化铀（UOF）的硝酸盐颗粒通过颗粒操作器转移到棉签上。然后，微萃取探头将 5%的硝酸（HNO）溶剂滴到棉签表面以萃取铀物种。然后将提取的样品送到 ICP-MS 进行同位素测定。铀信号的大部分（分别为 UO（NO）·6HO 和 UOF 的约 99%和约 94%）在最初的 15 s 萃取中被检测到，而在同一位置进行的后续萃取则没有或几乎没有 U 信号，表明固体铀化合物几乎已从棉签表面完全去除。对每种铀化合物进行了 10 个样品的分析，以确定其同位素组成。对于 UO（NO）·6HO，测定的同位素比值相对于参考同位素比值的相对偏差（% RD）分别为 U/U、U/U 和 U/U 的 0.97、1.0 和 7.3%。UOF 同位素比值的% RD 分别为 U/U 和 U/U 的 1.9%和 0.60%。U、U 和 U 的检测限分别为 0.002、0.4 和 60 pg。这项工作表明，微萃取 ICP-MS 是一种快速灵敏的方法，可以直接测定棉签上 UO（NO）·6HO 和 UOF 颗粒的铀同位素比值。
