使用化学分析法測定过磷酸盐中可溶性磷酸,需要較长时間,不能滿足工业的要求。为此,設法利用PO_4~(---)离子在滴汞电极上不起氧化还原反应的性貭,选擇在滴汞电极上能引起氧化还原作用的沉淀剂离子作为标准溶液,來滴定被分析溶液,然后观察因加入沉淀剂引起扩散电流的改变,获得等当点,再根据在等当点时消耗沉淀剂标准溶液的体积,来測定物貭中PO_4~(---)离子的含量。如所周知,PO_4~(---)离子与阳离子作用,能否形成沉淀,全视溶液的pH值而定,因此,选擇适当沉淀剂来进行沉淀PO_4~(---)离子时,調节溶液的pH值是极重要的。在 The use of chemical analysis of phosphate in the determination of soluble phosphate, takes a long time, can not meet the requirements of the industry. To this end, trying to use PO_4 ~ (---) ions in the mercury drop electrode can not afford the redox reaction 貭, select drop in the mercury electrode can cause redox role as a standard solution of precipitant ions to titrate Analyze the solution, and then observe the change of diffusion current caused by the addition of precipitating agent, obtain the equivalence point, and then determine the content of PO_4 ~ (---) ions in the target material according to the volume of the standard solution of the precipitating reagent consumed at the equivalent point . As we all know, PO_4 ~ (-) ions and the role of the cation, whether the formation of precipitation, depending on the pH value of the solution, therefore, the choice of a suitable precipitant for the precipitation of PO_4 ~ (---) ions, It is important to adjust the pH of the solution. in