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2-[3,5-二氯-2-吡啶)偶氮]-5-二氨基酚(简称3,5-dicl-DEPAP)用于锌的光度测定已有报道,但采用该试剂作为锌的络合滴定指示剂还未见报道。本文研究了3,5-dicl-DEPAP作为锌络合滴定指示剂的可能性。研究表明,在pH 5.6 HOAc-NaOAc介质中,加入2滴3,5-dicl-DEPAP指示剂,以EDTA标准溶液(0.01mol·L~(-1))对锌进行滴定,溶液颜色由紫红色变为亮黄色,终点突跃敏锐,准确度高。在拟定条件下对铜合金、试剂锌粒等样品中锌的测定及回收试验,获得满意结果。回收率为98.4～100.6%。
Photometric determination of zinc using 2- [3,5-dichloro-2-pyridyl) azo] -5-diaminophenol (abbreviated as 3,5-dicl-DEPAP) has been reported. However, Complexometric titration indicator has not been reported. This article investigates the possibility of 3,5-dicl-DEPAP as a zinc complexometric titration indicator. The results showed that in the pH 5.6 HOAc-NaOAc medium, 2 drops of 3,5-dicl-DEPAP indicator were added and titrated with EDTA standard solution (0.01 mol·L -1) Change to bright yellow, sudden sharp end point, high accuracy. In the proposed conditions for the copper alloy, zinc reagent samples and other zinc determination and recovery test, to obtain satisfactory results. The recovery rate was 98.4 ~ 100.6%.