自动电位滴定法精密测定镎含量

Accurate and Precise Determination of Neptunium by Means of Automatic Potentiometric Titration

镎是制备238Pu的重要原料。具有明确、清晰溯源性的镎的精密测定技术对于镎提取工艺研究和标准物质研制具有重要意义。本文提出了一种精密测定镎含量的新方法,即在1.0mol/L硫酸体系中,采用氧化银(Ⅱ)将镎氧化至Np(Ⅵ),过剩氧化银(Ⅱ)采用氨基磺酸破坏,采用Fe(Ⅱ)还原Np(Ⅵ)至Np(Ⅳ),过剩Fe(Ⅱ)采用标准重铬酸钾氧化的方式进行镎滴定条件研究,并确定了最佳实验条件,建立了自动电位滴定法精密测定镎的方法。镎取样量为5.0mg时,相对标准偏差为0.04%(n=6)。该方法溯源链清晰、取样量小、操作简便、准确度和精密度高,可用于镎标准物质的制备。

Neptunium is the raw material for 238 Pu preparation.The accurate determination method of neptunium with accurate and clear traceability is very important for the extraction process of neptunium and the preparation of neptunium standard material.A novel method for accurate and precise determination of neptunium was developed.First neptunium was oxidized to Np(Ⅵ)in 1.0 mol/L sulfuric acid solution by silver(Ⅱ)oxide and excess silver(Ⅱ)oxide was destroyed by sulfaminic acid,then Np(Ⅵ)was titrated to Np(Ⅳ)by Fe(Ⅱ),finally excess Fe(Ⅱ)was re-titrated by standard potassium dichromate solution.When neptunium is about 5.0 mg,a good precision is achieved with the relative standard division(RSD)of 0.04%.The method is clearly traceable,simple,precise,accurate and can be explored to prepare neptunium standard materials.