用络合滴定法测定天然水中的微量硫酸盐有多种方法。一般以 EDTA 为络合滴定剂,以 BaCl_2或 Pb(NO_3)_2为 SO_4~(2-)的沉淀剂。测定时可先将硫酸盐沉淀溶解,滴定与SO_4~(2-)反应的 Ba~(2+)或 Pb~(2+);亦可滴定过量的 Ba~(2+)或 Pb~(2+)。后者又有过滤或不过滤沉淀两种方式。由于 PbSO_4在水中的溶解度较大,常需加入有机溶剂以降低溶解度,一般应用不多。比较通用的是以 BaGl_2为沉淀剂的方法。但此法在实际使用中一般存在下列 There are many ways to determine trace sulfate in natural water by complexometric titration. Generally EDTA as a complex titrant to BaCl_2 or Pb (NO_3) _2 SO_4 ~ (2-) precipitating agent. In the determination, the precipitate of sulfate can be firstly dissolved and titrated with Ba2 + or Pb2 ​​+ reacted with SO4- (2-); titration of excess Ba2 + or Pb2 +). The latter filter or filter precipitation in two ways. Due to the large solubility of PbSO_4 in water, it is often necessary to add organic solvents to reduce the solubility, generally not much application. More common is based on BaGl_2 as a precipitating agent. However, this method generally exists in the actual use of the following