研究了铝合金中铜含量的示波滴定法.在酸性溶液中抗坏血酸将铜(Ⅱ)还原为铜(Ⅰ),用过量四苯硼钠沉淀铜(Ⅰ),过量的四苯硼钠用氯化四乙基铵标准溶液返滴定,以四苯硼钠切口消失为终点,计算出铜含量.方法终点变化敏锐,不外加指示剂,与标准分析方法相比较,操作简便、快速,所用分析试剂无毒,测定结果的RSD小于0.19%,标准加入回收率为98.7%-102.0%.

Oscillopolarographic titration was applied to the determination of copper in aluminum alloys.In a weakly acidic solution of the sample,Cu(Ⅱ) ion was reduced to Cu(Ⅰ) by ascorbic acid,and a definite amount of standard sodium tetraphenyl borate solution was added to precipitate Cu(Ⅰ) quantitatively.Excess of the tetraphenylborate solution was backtitrated with standard solution of tetraethyl ammonium chloride until the incision at the lower part of the oscillopolarogram of tetraphenyl borate instantly disappeared,indicating the approach of end-point of titration.Mass of copper found was calculated by the given formula.Test for precision with an aluminum alloy of known copper content (wCu 1.33%) for 5 successive determinations,the RSD found was 0.19%.Results of test for recovery by standard addition method were found in the range of 98.7%-102.0%.