以恒电流库仑分析法测定钢铁中砷含量

Determination of the Micro Arsenic in the Steel by the Constant Electric Current Coulometric Method

采用HClO4将钢铁中As氧化H3AsO4，用TiCl3将H3AsO4还原为HAsO2；电解KBr水溶液，使Pt阳极上电生成Br2，Br2与HAsO2定量反应，采用永停终点法确定库仑滴定终点。方法相对误差为0．143％～0．167％：RSD％（n=11）为0．028％，平均回收率为99．90％。

The micro arsenic in the steel was determind. The process were described： oxidizing as to H3AsO4 in the steel by the HClO4, reducing H3AsO4 to HAsO2 by theTiCl3 ;electrolysis the potassium bromide solution, to make the platinum anode producing the Br2 ; Br2 reacting with HAsO2 quantitatively. confirming end point of the titration by the forever stop end point method; calculateg arsenic content in the steel according to the electrolysis law. Relative error is 0.143% ～ 0.167%, （n = 11）is 0.028% ,average recovery rate is 99.90%.