染料交换荧光分光光度法测定地球化学样品中痕量铊

Determination of Trace Thallium in Geochemical Samples by Dye-Exchange Fluorescence Spectrophotometry

研究表明,在H_3PO_4介质中,丁基罗丹明B可从乙酸异戊酯有机相中的[TlBr_4]^--结晶紫缔合物中置换结晶紫而形成新的离子缔合三元荧光络合物。详细考察了该络合物形成的最佳条件、荧光特性及萃取溶剂等,制定了地球化学样品中痕量T1的荧光光度测定新方法,其检出限0.005μg/ml,Tl量在0～0.5μg/ml范围与荧光强度呈正比。测定了含Tl量0.61～1.9μg/g的8个一级地球化学标样,结果相符;RSD(n=5)为3.3％～12.6％;标样加标回收率为94％～105％。

It was found that the crystal violet dye in the [TlBr4] -crystal violet associate in amyl acetate phase can be displaced by butylrhodamine B in a H3PO4 medium,and a new fluorescence ternary complex was formed. A fluorescence spectrophotornetric method for the determination of trace Tl has been proposed which was based on the above investigation. The detection limit is 0. 005 μg/ml. The fluorescence intensity is in proportion to the concentration of Tl from 0 to 0. 5 fig/ml. The method has been tested on 8 geochemical standard samples with 0. 61 ~1. 9μg/g Tl and RSD(n = 5) is 3. 3%~12. 6%,with a recovery of 94%~~105%.