高灵敏度分光光度法测定岩石中微量钍和铀的研究

A STUDY ON DETERMINATION OF MICRO-AMOUT Th AND U IN ROCKS BY SENSITIVE SPECTROPHOTOMETRY

经研究在乙醇存在下钍与偶氮胂Ⅲ的高灵敏度显色反应,获得表观克分子吸光系数为1.43×10~5,络合物吸光度在24h 稳定,进一步探讨了乙醇的增敏机理。利用双波长系数倍率法使用5-Br-PADAP 测定铀的灵敏度提高6.5倍,获得表观克分子吸光系数为4.97×10~5。采用上述显色体系试验了 TBP 萃取色层分离钍铀的适宜条件,提出的方法用于岩石中微量钍和铀的测定,经标准样品分析,结果与推荐值相符。

This article studies a high - sensitive colour reaction between Th and arsenazo III in the presence of alcohol. The apparent molar absorptivity obtained for thorium, is 1.43×105L· mol-1·cm-1, the absorbance of the complex is stable in 24h. The mechanism of reaction in this system has beem investigated. The determination of U with 5-Br-PADAP has been investigated by dual-wavelenth spectrophotometric method. The apparent molar absorptivity obtained by using the differences in absorbance is 4.97×05L·mol-1·cm-1. The extractive chromatographic separation for Th and U with TBP-containing Resin as stationary phase, and HC1 and H2O as mobile phase is studied, We use 3 mol/L HC1 elution Th and H2O elution to separate U, so that a good result was obtained. In order to ensure the separation 20℃ is selected to control the flow rate being less than 1 ml/ min. The standard recovery results ars quite satisfactory. The proposed procedure has been applied to determination of micro-amount Th and U in rocks, and standard rock samples analysis values are similar to published values.