在聚乙烯醇存在于铂(Ⅳ)-钨酸盐-罗丹明B体系光度法测定铂

Spectrophotometric Determination of Platinum with Platinum(Ⅳ)-Tungstate-Rhodamine B System in the Presence of Polyvinyl Alcohol

研究了在聚乙烯醇（ＰＶＡ）存在下钨酸盐和罗丹明Ｂ（ＲＢ）光度法测定铂，铂（Ⅳ）与钨酸铵和罗丹明Ｂ形成离子缔合物，它的最大吸收波长位于５７０ｎｍ，摩尔吸光系数ε值为３．４１×１０７Ｌ·ｍｏｌ－１·ｃｍ－１，铂量在０～０．１１μｇ／２５ｍｌ范围内服从比耳定律，缔合物至少稳定９６ｈ，缔合物的摩尔比为Ｐｔ（Ⅳ）：ＲＢ＝１：４，考察了５０多种共存离子的影响，大多数元素不干扰。测定铂（Ⅳ）的适宜条件为［Ｈ２ＳＯ４］＝１．３ｍｏｌ／Ｌ，［ＷＯ４２－］＝１．２×１０－４ｍｏｌ／Ｌ，［ＲＢ］＝４．２×１０－５ｍｏｌ／Ｌ，０．０８％ＰＶＡ。本法已用于铂矿中铂的测定，结果满意。

Spectrophotometric determination of platinum has been studied with tungstate and rhodamine B in the presence of polyvinyl alcohol.Platinum(Ⅳ) reacts with ammonium tungstate and rhodamine B(RB) to form the ion associated complex.Its apparent molar absorptivity is 3.41×10 7L·mol -1 ·cm -1 at 570nm.Beer's low is obeyed in the range of 0 to 0.11μg/25ml for platinum.The ion associated complex is stable for at least 96h.the molar ratio of Pt(Ⅳ) to RB in the ion associated complex was established to be l:4.The influence of diverse 50 ions was examined.Most ions do not interfere.The optimum conditions for determination of platinum are [H 2SO 4]=1.3mol/L,[WO 4 2- ]=1.2×10 -4 mol/L,=4.2×10 -5 mol/L and 0.08%PVA.The method is satisfactorily applied to the determination of platinum in some minerals.