锡钨杂多酸-耐尔蓝光度法测定纳克量锡

Spectrophotometric Determination of Nanogram Amounts of Tin(Ⅳ)with Heteropoly Tinotungstic Acid and Nile Blue

本文报道一个光度法测定纳克量锡的新方法。在聚乙烯醇（ＰＶＡ）存在下锡（Ⅳ）与钨酸盐和耐尔蓝（ＮＢ）反应形成离子缔合物，离子缔合物的最大吸收位于５８０ｎｍ，表观摩尔吸光系数ε值２．９５×１０７Ｌ·ｍｏ１－１·ｃｍ－１，服从比耳定律范围０～２．０μｇ／Ｌ，检出限（３σ）０．０８３μｇ／Ｌ（ｎ＝１０），对２．０μｇ／Ｌ锡测定的ＲＳＤ为１．４２％（ｎ＝１１），离子缔合物至少稳定７２ｈ。考察了４０多种共存离子的影响，大多数常见元素不干扰。测定锡的适宜条件［Ｈ２ＳＯ４］＝１．２０ｍｏ１／Ｌ，［ＷＯ２－４］＝６．０５×１０－５ｍｏ１／Ｌ，［ＮＢ］＝５．５×１０－５ｍｏ１／Ｌ和ＰＶＡ０．０８％。本法已用于某些合金钢和锌合金中纳克量锡的测定，结果与推荐值吻合，回收率满意。

A new spectrophotometric method for the determination of nanogram amounts of tin(Ⅳ)is developed based on the reaction of tin(Ⅳ)with tungstate and nile blue(NB) to form and ion association complex in the presence of polyvinyl alcohol(PVA). The ion-association complex exhibits maxium absorptivity at 580nm with apparent molar absorption coefficient was 2.95×10 7L·mol -1 ·cm -1 . Beer's law was obeyed over the concentration range of 0￣2.0μg/L. The detection limit(3σ)is 0.083(g/L(n=10) and the relative standard deviation of 2.0μg/L of tin(Ⅳ)is 1.42%(n=11). The ion association complex is stable for at least 72h. Over 40 foreign ions were tested for interference. Most common ions do not interfere. The optimum conditions for the determination of tin(Ⅳ)are 1.20mol/L of H 2SO 4, 6.05×10 -5 mol/L of WO 2- 4, 5.5×10 -5 mol/L of NB and 0.08% PVA. The method has been applied to the determination of nanogram amounts of tin(Ⅳ)in some steels and zinc based alloys samples. The results obtained agree well with recommended values and the recovery is statisfied.