钪-乳酸-2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚-Triton-X-100体系的显色反应及应用研究

Study on Chromogenic Reaction of Scandium-Lactic Acid-2-(5-Bromo-2-pyridyIazo)-5-diethyIaminophenoI-Triton X-100 System and Its Application

在pH8.1～8.8,有 Triton X-100存在下,Sc(Ⅱ)与乳酸(L)及 5-Br-PADAP(R)形成胶束混配络合物。该络合物最大吸收波长为565nm,表观摩尔吸光系数为6.08×10～4L·mol～(-1)·cm(-1)。络合物组成为Sc:L:R=1:1:2。由于乳酸的存在,显色体系灵敏度和选择性都得到提高。本法用PMBP萃取分离干扰组分后,可测定钨矿及其浸出渣中微量钪,相对标准偏差为1.7％～2.7％。

In the presence of Triton X-100, scandium( III ) reacts with lactic acid and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) at pH 8. 1-8. 8 to form a mixedligand complex of the micellae with an apparent molar absorptivity of 6. 08×104 L· mol-1· cm-1 (565 nm). The molar ratio of Sc ( Ⅲ ) to lactic acid to 5-Br-PADAP is found to be 1 : 1 : 2. Because lactic acid of appropriate amounts was added, the sensitivity and selectivity of colour reaction of Sc( Ⅲ ) with 5-Br-PADAP were enhanced. The proposed method has been used to determine trace scandium in tungsten ores and its extractive dregs after previous separation of interference ions with extraction of PMBP. The relative standard deviation is1.7%-2.7%.