【摘要】 研究了２－〔２－（５－溴吡啶）偶氮〕－５－二甲氨基苯胺（简称５－Ｂｒ－ＰＡＤＭＡ）与Ｐｔ（ＩＶ）配合物的光度特性和显色反应的最佳条件。在ｐＨ３５～４８ＨＡｃ－ＮａＡｃ缓冲介质中，沸水浴加热２０ｍｉｎ，Ｐｔ（ＩＶ）与５－Ｂｒ－ＰＡＤＭＡ形成１：３的紫红色配合物。配合物形成后，提高酸度为０８～３６ｍｏｌ·Ｌ－１盐酸溶液，最大吸收波长红移至６２０ｎｍ，灵敏度和对比度显著提高，表观摩尔吸光系数ε６２０＝６５×１０４Ｌ·ｍｏｌ－１·ｃｍ－１，对比度λ＝１８６ｎｍ。Ｐｔ（ＩＶ）浓度在０～２８μｇ／２５ｍｌ遵守比尔定律。大多数常见金属离子不干扰Ｐｔ的测定，可满意地应用于催化剂中微量Ｐｔ的测定。更多还原

【Abstract】 The reaction of platinum(IV) with 2- 2-(5-bromopyridyl)azo -5-dimethylaminoaniline(5-Br-PADMA)has been studied. It was found that the complex reaction can be completed within 18～40 min, at the conditions of 100℃ and pH=4.2 kept in a HAc-NaAc buffer solution. The maximum absorption of the complex is 620 nm in a solution of 0 8～3 6mol/LHCl. Its apparent molar absorptivity is ε 620 =6 5×10 4L·mol -1 ·cm -1 . Beer′s law is obeyed in the range of 0～28μg/25ml for platinum(IV) with r=0 9996. The molar ratio of platinum(IV)to 5-Br-PADMA is established to be 1∶3 by two methods. The methods are highly selective. Most common ions do not interfere. The methods have been applied to the determination of trace platinum in platinum catalysts with satisfactory results.更多还原