本文将前文提出的用高灵敏度的Tb~(3+)-Tiron荧光络合物指示等当点的非常规络合滴定原理,用于几微克铀的络合滴定,着重研究了定量地还原铀(Ⅵ)至铀(Ⅳ)的适宜条件,观察了测定的相对标准偏差。两个铀矿标样中的铀是用TBP萃淋树脂柱色层法分离后测定的,准确度和精密度均在0.5％以内。 In this paper, the previously proposed unconventional complexometric titration with the highly sensitive Tb ~ (3 +) - Tiron fluorescent complex at equivalent points was applied to the complexometric titration of several micrograms of uranium with emphasis on the quantitative reduction of uranium (Ⅵ) to uranium (Ⅳ), and the relative standard deviations (RSDs) were observed. The uranium in the two uranium standard samples was determined by TBP extraction resin column chromatography with accuracy and precision within 0.5%.