National Institute of Standards and Technology, 100 Bureau Drive, Mail Stop 8462, Gaithersburg, MD, 20899, USA.
Lawrence Livermore National Laboratory, P.O. Box 808, L-231, Livermore, CA, 94551-0808, USA.
Talanta. 2021 Jan 1;221:121638. doi: 10.1016/j.talanta.2020.121638. Epub 2020 Sep 8.
A highly-enriched U reference material (>0.99987 n(U)/n(U)) has been prepared and characterized for use as an isotope dilution mass spectrometry spike. An ion exchange separation was performed on 1 g of high purity U to further reduce trace amounts of contaminant Pu in the material. The purified U was then prepared as a master solution which was analyzed for molality of uranium by modified Davies and Gray titration. A portion of the master solution was quantitatively diluted and dispensed for reference material units. Selected units were analyzed for verification of uranium amount and to characterize uranium isotope amount ratios by multi-collector inductively couple plasma mass spectrometry. Modelling of spike-corrected isotopic data show that the new spike will enable simultaneous measurements of uranium amount and isotope amount ratios with resulting uncertainties that are substantially less sensitive to over spiking than widely used U certified reference materials.
已制备并表征了一种高浓铀参考物质（>0.99987 n(U)/n(U)），可作为同位素稀释质谱法的内标使用。对 1 克高纯度铀进行离子交换分离，以进一步减少材料中痕量的 Pu 污染物。然后将纯化的铀制备成母液，通过改良的 Davies 和 Gray 滴定法分析铀的克分子浓度。母液的一部分被定量稀释并分发给参考物质单位。选择部分单位进行分析，以验证铀的量，并通过多接收电感耦合等离子体质谱法表征铀同位素丰度比。对加标校正后同位素数据的建模表明，新的内标将能够同时测量铀的量和同位素丰度比，与广泛使用的 U 认证参考物质相比，其不确定度对加标过量的敏感性要小得多。
