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2-(2-吡啶偶氮)-5-二乙氨基苯酚(PA-DAP)与它的衍生物是一类与PAR具有相同螯合结构的灵敏显色剂.由于在其偶氮对位的苯环引入了强斥电子基团—二乙胺基,因此与过渡元素的显色反应灵敏度甚高.镍与5-Br-PADAP形成1:2的有色络合物,在波长570纳米处,摩尔吸光系数为1.17×10~5升·摩尔~(-1)·厘米~(-1).比PAR法约高1倍,与常用的丁二酮肟法相比约高7～8倍,是目前测定镍的最灵敏试剂之一.文献对镍与5-Br-PADAP络合物的分光光度特性进行过研究,并使用掩蔽剂消除铝及
2- (2-Pyridylazo) -5-diethylaminophenol (PA-DAP) and its derivatives are a kind of sensitive reagent with the same chelate structure as PAR. The benzene ring introduces a strong electron-withdrawing group, diethylamino, and therefore has a high sensitivity to the color reaction with transition elements. Nickel forms a 1: 2 colored complex with 5-Br-PADAP at a wavelength of 570 nm, The molar extinction coefficient is 1.17 × 10 ~ 5 L · mol -1 · cm -1, which is about 1 time higher than that of PAR method and about 7 ~ 8 times higher than that of the conventional dimethylglyoxime method. One of the most sensitive reagents for the determination of nickel is currently in the literature.The literature studies the spectrophotometric properties of nickel and 5-Br-PADAP complexes and uses masking agents to eliminate aluminum and