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在酸性溶液中用EDTA直接法测定大量锆时,由于锆氧离子极易发生聚合作用而使滴定时EDTA消耗量降低以及产生返色现象。在盐酸溶液中经强热处理后,虽然能使绝大部分锆氧离子解聚,但并不彻底。因此,用EDTA滴定锆时,不是全部按1:1络合关系进行,其差别和被滴定溶液的体积及锆存在的量均有关系。通常滴定误差可达2～3%。同时,由于锆石试样的分解多采用氟化物盐类,引进的氟离子强烈干扰终点的确定,因而必须采取沉淀过滤的方法加以除去,增加了操作手续。
Determination of a large amount of zirconium by EDTA direct method in an acidic solution results in a decrease in EDTA consumption and a return of color due to the extreme polymerization of zirconium ions. In the hydrochloric acid solution after heat treatment, although most of zirconium ion can depolymerization, but not completely. Therefore, titration of zirconium with EDTA, not all in 1: 1 complex relationship, the difference between the titration solution volume and the amount of zirconium are related. Titration error is usually up to 2 to 3%. At the same time, fluoride salts are mostly used in the decomposition of zircon samples. The introduction of fluoride ion strongly interferes with the determination of the end point. Therefore, it must be removed by sedimentation filtration and added to the operating procedures.