用罗丹明B和钼酸铵水相光度法测定痕量锇

Spectrophotometric Determination ofOsmium by Reaction With Molybdate andRhodamine B in the Preswnce of PVA

本文研究在聚乙烯醇（ＰＶＡ）存在下，锇（Ⅷ）与钼酸铵形成络阴离子，继而与罗丹明Ｂ（ＲＢ）形成离子缔合物。该缔合物的摩尔吸光系数ε值为２．６２×１０￣６Ｌ·ｍｏｌ￣（－１）·ｃｍ￣（－１），性范围０～１．２μｇ／２５ｍＬ，检测限为１．３ｎｇ／ｍＬ（ｎ＝８），ＲＳＤ为２．２％（ｎ＝７），缔合物稳定４周。考察了３０多种共存离子的影响，除贵金属和能形成杂多酸的元素外，大多数贱金属不干扰。方法已用于测定某些催化剂和岩矿中的锇，结果满意。研究了缔合物组成的摩尔比和红外光谱。

new spectrophotometric method forthe determinadon of osmium has been devel-oped,based on the reaction of osmium withmolybdate and rhodamine B(RB)to form anion-associated complex in the presence ofpolyvinyl alcohol(PVA).The molar absorp-tivity is 2.62 ×10￣6 L. mol￣(-1)cm￣(-1).Beer's lawis obeyed over the range of 0～1.2μg/25mL. The relative standard deviation evaluatedfrom seven independent determinations of0.4μg/mL of osmium is 2.2%。The limit ofdetection is 1.3ng/mL(n=8). The colorspecies is stable for more than 4 weeks. Over 30 foreign rons were tested for interfer-ence,other noble metal ions,sb(Ⅲ),Ge(Ⅳ),Ti(Ⅳ),Zr(Ⅳ)and Hf(Ⅳ)inferferedand had to be separated from osmium by dis-tillation.The method can be applied to thespectrophotometric determination of traceamounts of osmium in some catalyst andores.