EDTA络合滴定法测定黄铜中铜和锌

对EDTA络合滴定法测定黄铜中的铜和锌条件进行了研究,并建立了一种连续测定黄铜中铜和锌的简单方法。通过硫代硫酸钠对铜离子的配位掩蔽,在pH 5.5时,以1-(2-吡啶偶氮)-2-萘酚(PAN)作指示剂,用EDTA标准溶液滴定溶液中的锌,根据消耗EDTA标准溶液的体积得到锌的含量;同时以PAN作指示剂,用EDTA标准溶液滴定溶液中铜和锌,根据滴定铜和锌与滴定锌消耗EDTA标准溶液的体积差值,得到铜的含量。方法应用于黄铜标准物质中铜和锌的测定,测定值与认定值相一致。对样品进行精密度试验,得到铜和锌测定结果的相对标准偏差(RSD)均不大于0.55%(n=10)。

Determination of copper and zinc in brass by EDTA complexometric titration

The experimental conditions for the determination of copper and zinc in brass by EDTA complexometric titration were studied. A simple method for the continuous determination of copper and zinc in brass was established. The sodium thiosulfate was used for the coordination masking of copper ions. The zinc ions in solution were titrated with EDTA standard solution at pH 5.5 using 1-(2-pyridineazo)-2-naphthol (PAN) as indicator. The content of zinc was calculated based on the consumed volume of EDTA standard solution. Meanwhile, the copper and zinc ions in solution were titrated with EDTA standard solution using 1-(2-pyridineazo)-2-naphthol (PAN) as indicator. The content of copper could be calculated based on volume difference of consumed EDTA standard solution for the titration of copper and zinc and the titration of zinc. The proposed method was applied to the determination of copper and zinc in certified reference materials of brass, and the found results were consistent with the certified values. The precision test of sample was also conducted. The relative standard deviations (RSD, n=10) of copper and zinc were both less than 0.55%.