Abstract This paper presented thorium and neptunium quantification of a new synthesized powder, a (Th,Np)O2 mixed oxide. Thorium was quantified by Thermal Ionization Mass Spectrometry using Isotope Dilution (ID-TIMS) which is one of the most accurate methodology to determine actinide mass fraction. The (sample-spike) mixture isotope ratio was measured using the TIMS reference method for major isotope ratio determination, i.e. the total evaporation method. An expanded uncertainty below 1% was estimated for the Th mass fraction. The study of the uncertainty sources showed that the main one comes from the spike mass fraction uncertainty. As Np quantification with ID-TIMS is difficult due to the lack of commercially-available spike solution, the Np mass fraction was obtained by ICP-MS measurements using a gravimetric standard addition method combined with an analytical internal standard. The developed method used an element initially present in the sample, here Th, as an internal standard for ICP-MS measurements. This helps reducing the number of manipulation as well as cross contamination, which is an important risk when experiments are performed in glove boxes. Also, equations are simplified. An expected uncertainty about 1.8% was estimated for Np. Finally, the Th–Np mixed oxide was found to have a Th0.4836(50)Np0.5164(50)O2 stoichiometry. This study can be extended to other complicated samples or to the characterization of in-house certified reference material.

中文翻译：

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对 Th0.5Np0.5O2 钍镎混合氧化物分析的 TIMS 和 ICP-MS 组合研究

摘要 本文介绍了一种新型合成粉末（一种 (Th,Np)O2 混合氧化物）的钍和镎定量分析。钍通过使用同位素稀释 (ID-TIMS) 的热电离质谱法进行定量，ID-TIMS 是确定锕系元素质量分数的最准确方法之一。使用主要同位素比率测定的 TIMS 参考方法（即总蒸发法）测量（样品-加标）混合物同位素比率。估计 Th 质量分数的扩展不确定度低于 1%。不确定性来源的研究表明，主要来源是尖峰质量分数的不确定性。由于缺乏市售的加标溶液，使用 ID-TIMS 进行 Np 量化很困难，Np 质量分数是通过 ICP-MS 测量获得的，使用重量标准添加方法结合分析内标。开发的方法使用最初存在于样品中的元素（此处为 Th）作为 ICP-MS 测量的内标。这有助于减少操作次数和交叉污染，这是在手套箱中进行实验时的一个重要风险。此外，方程被简化。估计 Np 的预期不确定性约为 1.8%。最后，发现 Th-Np 混合氧化物具有 Th0.4836(50)Np0.5164(50)O2 化学计量。这项研究可以扩展到其他复杂的样品或内部认证参考材料的表征。作为 ICP-MS 测量的内标。这有助于减少操作次数和交叉污染，这是在手套箱中进行实验时的一个重要风险。此外，方程被简化。估计 Np 的预期不确定性约为 1.8%。最后，发现 Th-Np 混合氧化物具有 Th0.4836(50)Np0.5164(50)O2 化学计量。这项研究可以扩展到其他复杂的样品或内部认证参考材料的表征。作为 ICP-MS 测量的内标。这有助于减少操作次数和交叉污染，这是在手套箱中进行实验时的一个重要风险。此外，方程被简化。估计 Np 的预期不确定性约为 1.8%。最后，发现 Th-Np 混合氧化物具有 Th0.4836(50)Np0.5164(50)O2 化学计量。这项研究可以扩展到其他复杂的样品或内部认证参考材料的表征。5164(50)O2 化学计量。这项研究可以扩展到其他复杂的样品或内部认证参考材料的表征。5164(50)O2 化学计量。这项研究可以扩展到其他复杂的样品或内部认证参考材料的表征。