2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺分光光度法同时测定铂与钯  

Simultaneous determination of platinum Ⅳ and palladium(Ⅱ) by spectrophotometry with 2-(5-bromo-2-pyridylazo)-5-dimethylaniline

作　　者：韩权[1,2] 霍燕燕[2] 王媚[1] 杨晓慧[1] 

机构地区：[1]西安文理学院化学系,陕西西安710065 [2]延安大学化学与化工学院,陕西延安716000

出　　处：《冶金分析》2009年第9期55-59,共5页Metallurgical Analysis

摘　　要：提出了以2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺(5-Br-PADAM)作显色剂光度法同时测定铂和钯的新方法。在0.2～3.0mol/L高氯酸介质中,Pd(Ⅱ)与5-Br-PADAM可形成稳定的络合物,其最大吸收波长位于609nm处;在pH3.5～4.8的弱酸性介质中,Pt(与5-Br-PADAM定量反应,铂络合物形成后非常稳定,以强酸酸化可转化为另一种质子化型体。在609nm处,二者的吸光度具有良好的加和性。基于二者显色酸度的差异,建立了铂、钯同时测定新方法,显色反应的摩尔吸光系数分别为εPd=8.2×104L.mol-1.cm-1和εPt=5.5×104L.mol-1.cm-1。铂、钯浓度分别在0～1.1mg/L和0～1.4mg/L符合比尔定律。方法用于合金和催化剂中微量铂和钯的同时测定,结果与AAS法测定结果相符,相对标准偏差在0.50%～2.0%之间。A novel method for the determination of platinum and palladium by spectrophotometry with 2-（5-bromo-2-pyridylazo）-5-dimethylaniline （5-Br-PADAM） was developed. In 0. 2--3.0 mol/L of perchloric acid medium, Pd （II） could react with 5-Br-PADAM to form a stable complex which had maximal absorption wavelength at 609 nm. In weak acid medium at pH 3. 5--4, 8, Pt （IV） could quantitatively react with 5-Br-PADAM. The formed platinum complex was very stable, which could be transformed to another kind of protonized body by strong-acid acidification. Their absorbencies exhibited good additivJty at 609 nm. In the basis of the difference of acidity for coloring, a novel determination method of platinum and palladium was established. The molar absorption coefficients were eea=8.2×10^4 L · tool^-1 · cm^-1 and εPt=5.5× 10^4 L · mol^-1 · cm^-1, respectively. Beer＇s law was obeyed for platinum and palladium in the range of 0--1.1 mg/L and 0--1.4 mg/L. The proposed method was applied to the simultaneous determination of trace platinum and palladium in alloy and catalyst. The determination results were in good agreement with those obtained by AAS. The relative standard deviations （RSD） were 0.50 %--2.0 %.

关 键 词：2-(5-溴-2-吡啶偶氮)-5-二甲氨基苯胺 分光光度法 同时测定 铂 钯 

分 类 号：O657.32[理学—分析化学]