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本文研究了一种高灵敏度的直接分光光度测定痕量铀的新方法。它是在非离子型表面活性剂吐温—40存在下,在pH 8.0下,铀(Ⅵ)与2—(3,5—二溴—2—吡啶偶氮)—5—二甲氨基苯酚形成一种摩尔比为1:2的兰绿色络合物,其特征吸收波长为λ_(max)=670um,摩尔吸光系数ε=1.4×10~5,络合物的条件稳定常数K_稳=3.0×10~(11),在10—50倍于铀的20多种常见重金属离子存在下,不经分离可直接测定微量铀。此方法适用于水、矿石等样品中铀的测定,精密度优于±5.0%,加入回收率大于95%。
In this paper, a new method of direct spectrophotometric determination of trace uranium with high sensitivity was studied. It is formed from uranium (VI) and 2- (3,5-dibromo-2-pyridylazo) -5-dimethylaminophenol in the presence of the non-ionic surfactant Tween-40 at pH 8.0 A blue-green complex with a molar ratio of 1: 2 has a characteristic absorption wavelength of λ max = 670 μm, a molar absorptivity ε = 1.4 × 10 -5, and a stable condition constant K 3.0 for the complex × 10 ~ (11), uranium in 10-50 times more than 20 common heavy metal ions in the presence of uranium can be directly measured without isolation. The method is suitable for the determination of uranium in water, ore and other samples with the precision of better than ± 5.0% and the recovery of more than 95%.