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本文研究了新显色剂-2-〔2- (3,5-二溴吡啶)偶氮〕-5-二乙氨基苯甲酸(3, 5-diBr-PAEB)与钴的显色反应。在pH2.1—5.4的Triton X-l00介质中,钴可与3,5-diBr-PAEB形成稳定的绿色配合物。其最大吸收峰位于673nm,摩尔吸光率5_(673)=1.52×10~5L.mol~(-1)·m~(-1)。反应具有较好的选择性,共存元素中,仅铜、镍、铁、锰、钒等有一定干扰,其它金属离子在一定限量内对钴的显色反应没有干扰。而上述干扰离子也可采用适当的掩蔽剂消除影响。因此,反应可直接用于各种钢铁试样中微量钴的分光光度法测定。结果堪称满意。
In this paper, the color reaction of 2- (2- (3,5-dibromopyridine) azo] -5-diethylaminobenzoic acid (3, 5-diBr-PAEB) with cobalt was studied. Cobalt can form a stable green complex with 3,5-diBr-PAEB in Triton X-l00 medium at pH 2.1-5.4. The maximum absorption peak was at 673 nm, and the molar absorptivity was 5 673 = 1.52 × 10 5 L · mol -1 (-1) m -1. The reaction has good selectivity. Among the coexisting elements, only copper, nickel, iron, manganese, vanadium and so on have certain interference, while other metal ions do not interfere with the color reaction of cobalt within a certain limit. The above interfering ions can also be removed using an appropriate masking agent. Therefore, the reaction can be directly used for the determination of trace cobalt in various steel samples by spectrophotometry. The result is satisfactory.