碲钨杂多酸-丁基罗丹明B超高灵敏显色反应的研究

Study on Ultrasensitive Color Reaction of Tellurium(Ⅳ) with Butylrhodamine B and Tungstotelluric Heteropolyacid

聚乙烯醇存在下，碲与钨酸钠形成碲钨杂多酸，继而与丁基罗丹明Ｂ（ＢＲＢ）形成离子缔合物。离子缔合物的最大吸收位于５６５ｎｍ，表观摩尔吸光系数ε值为１．８８×１０７Ｌ·ｍｏｌ－１·ｃｍ－１，服从比耳定律范围０～５．６μｇ／Ｌ，对０．１０μｇ／２５ｍＬＴｅ（Ⅳ）测定的相对标准偏差为１．０３％（ｎ＝１０）。离子缔合物至少稳定３０天。测定碲的适宜条件为ｃＨ２ＳＯ４＝１．４４ｍｏｌ／Ｌ，ｃＷＯ２－４＝１．２１×１０－４ｍｏｌ／Ｌ，ｃＢＲＢ＝５．２３×１０－５ｍｏｌ／Ｌ和ＰＶＡ０．０８％。考察了４０多种共存离子的影响，大多数常见离子不干扰，容许５００倍量Ｓｅ（Ⅳ）、５０倍量Ｃｕ（Ⅱ）、Ｂｉ（Ⅲ）存在。本法已用于某些烟尘中碲的测定，结果与电分析法吻合。

Tellurium(Ⅳ) reacts with sodium tungstate to form a tungstotelluric heteropolyacid complex.The ionassociation complex of tungstotelluric heteropoly species with butylrhodamine B(BRB) is formed in the presence of polyvinyl alcohol.The ionassociation complex exhibits maximum absorbance at 565nm,with an apparent molar absorptivity of 1.88×107dm3·mol-1·cm-1.Beer's law is obeyed in the range of 0 to 5.6μg/L for tellurium(Ⅳ).The relative standard deviation evaluated from determination of 0.10μg/25mL for Te(Ⅳ) is 1.03% (n=10).The ionassociation complex was stable for>30days.The optimum conditions for the determination of Te(Ⅳ) are H_2SO_4 1.44mol/L,WO_2-41.21×10-4mol/L,BRB 5.3×10-5mol/L,and PVA 0.08%.Over 40 foreign ions were tested for interference.Most common ions did not interfere,and 500fold amounts of Se(Ⅳ) or 50fold amounts of Cu(Ⅱ) and Bi(Ⅲ) could be tolerated.The method has been satisfactorily applied to the determination of Te(Ⅳ) in some smoke ash samples.The results obtained agreed well with those by electroanalytical method.