研究了2-(5-碘-2-吡啶偶氮)-5-二甲氨基苯胺(5-I-PADMA)与Pt(Ⅳ)显色反应,建立了一种测定微量铂的光度分析新方法。在p H4.3的HAc-NaAc缓冲溶液中,Pt(Ⅳ)与5-I-PADMA形成稳定的紫红色配合物,该配合物的最大吸收峰位于625nm,表观摩尔吸光系数为4.55×104L.mol-1.cm-1,铂(Ⅳ)含量在0—1.4μg.mL-1范围内符合比尔定律。方法应用于催化剂中微量铂的测定,结果满意。 The color reaction of 2- (5-iodo-2-pyridylazo) -5-dimethylaminoaniline (5-I-PADMA) with Pt (Ⅳ) was studied and a new spectrophotometric method for the determination of trace platinum . In the HAc-NaAc buffer solution of p H4.3, Pt (Ⅳ) and 5-I-PADMA form a stable purple complex, the maximum absorption peak of the complex is located at 625nm, the apparent molar absorptivity is 4.55 × 104L .mol-1.cm-1, the content of platinum (Ⅳ) in the range of 0-1.4μg.mL-1 Beer’s law. The method was applied to the determination of trace platinum in the catalyst with satisfactory results.