在用EDTA容量法测定矿样中Bi的过程中,原方法采用在滴定前一次性调节pH值后EDTA直接滴定。这种做法一方面难以控制pH值的最佳范围;另一方面随着滴定体积的增大,会改变其pH值,同时还会引起其它杂质元素的干扰,造成终点不够敏锐清晰,结果波动较大。为此,笔者对原方法稍加改进,使测定结果波动减小。 试样溶液经过滤后,移取10～20ml于250ml In the determination of Bi with EDTA volumetric method in the sample, the original method used in the titration before the one-time adjustment of pH EDTA titration. On the other hand, the volume of titration changes the pH of the titrant. At the same time, it can also cause the interference of other impurity elements, resulting in the end point being less sensitive and clear. The result is more volatile Big. To this end, the author of the original method a little improvement, so that the measurement results to reduce fluctuations. After the sample solution is filtered, remove 10 ~ 20ml in 250ml