硝酸锶-铬酸铅容量法测定干电池锌筒中的铅

Determination of lead in zinc can of primary battery by means of strontium nitrate-lead chromate capacity method

应用氧化 还原滴定原理 ,对干电池锌筒中铅的测定进行了探讨。采用硝酸锶作凝聚剂的新方法 ,加入过量的重铬酸钾标准溶液 ,在 pH为 3～ 4的醋酸缓冲溶液中 ,使得溶液中的铅定量生成铬酸铅沉淀 ,剩余的重铬酸钾在不分离铬酸铅的条件下 ,提高溶液酸度 ,以N 苯代氨基苯甲酸作指示剂 ,直接用硫酸亚铁铵标准溶液氧化还原滴定测定铅。试验表明该法操作简便、快速 ,无氰污染 ,不需昂贵的分析仪器 ,并具有良好的重现性 ,测定铅的标准偏差≤ 0 .0 0 1347,相对标准偏差≤ 0 .45 2 8% ,标准加入法的回收率为 99.6 1%～ 99.95 % ,平均为 99.80 %。

The determination of lead in zinc can of primary battery by means of oxidation reduction titration principle is discussed. A new method for the determination is introduced. Added excess amount of potassium dichromate standard solution to strontium nitrate, which is selected as the coacervation reagent, and added the acetic buffer solution with the pH value within 3-4 to make the lead in the solution synthesized into lead chromate for precipitating. Then increased the acidity of the remained solution without separating the lead chromate, and carried out the oxidation reduction titration with ammonium ferrous sulfate standard solution by adopting N phenylanthranilic acid as the indicator to determine the lead. The method is simple, quick and reliable for operation, away form cyanide pollution, and does not need expensive analytical instrument. The experimental results show that the standard deviation of determination of lead is not more than 0.001 347; the relative standard deviation is not more than 0.452 8%; the recovery rate by the standard addition is 99.61%-99.95%; and the average recovery rate is 99.08%.