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铬的测定,无论在钢铁分析还是在环境分析中都具有重要意义.二苯卡巴肼法是目前广泛用于钢铁等物质中铬的测定方法.该法灵敏度较高(ε_(540)=34600),选择性也较好.但是需将Cr(Ⅲ)氧化为Cr(Ⅵ)后再显色,而且显色剂本身稳定性差.最近十几年来,有人研究了Cr(Ⅲ)与PAN,PAR,铬菁R,二甲酚橙,偶氮胂Ⅲ等的显色反应.这些试剂灵敏度均较低,而且分析钢铁样品时,分离除去干扰离子的方法比较麻烦.2-[(5-溴-2-吡啶)偶氮]-5-(二乙基氨基苯酚)(简称5-Br-PADAP)是一种高灵敏的显色试剂.室温下能与许多金属离子生成易被氯仿萃取的有色络合物.在实验中我们发现,5-Br-PADAP与Cr(Ⅲ)可在加热时反应,
Determination of chromium, both in the steel analysis and environmental analysis are of great significance.Diphenylcarbazide method is currently widely used in the determination of chromium and other substances in chromium.The method has a high sensitivity (ε 540 (= 34600) However, the Cr (Ⅲ) should be oxidized to Cr (Ⅵ) before it is colored, and the stability of the colorant itself is poor. In the recent ten years, Chromocyanine R, xylenol orange, arsenazo Ⅲ etc. The sensitivity of these reagents are low, and the analysis of steel samples, the method of separation and removal of interfering ions is too cumbersome.2 - [(5-bromo-2 -pyridine) azo] -5- (diethylaminophenol) (abbreviated as 5-Br-PADAP) is a highly sensitive chromogenic reagent that is capable of generating colored complex with many metal ions easily chloroform-extracted at room temperature In the experiment, we found that 5-Br-PADAP and Cr (Ⅲ) can react on heating,