丁二酮肟分离-EDTA络合返滴定法测定哈氏合金中的镍

Determination of nickel in hastelloy alloy by dimethylglyoxime separation-EDTA complex back titration

哈氏合金样品用氢氟酸和硝酸加热溶解,用丁二酮肟沉淀镍,使其与铬、铁、钨等干扰元素分离,沉淀溶于盐酸,加入过量的EDTA标准溶液,以二甲酚橙为指示剂,在PH=5.5~6的HAC-NaAC缓冲介质中用标准Zn盐溶液返滴定.该方法具有良好的精密度,准确度高,能够满足哈氏合金样品中镍含量的测定要求.

Hydrofluoric acid and nitric acid were used to solubilize hastelloy alloy,and then dimethylglyoxime was used to precipitate Ni 2＋so that Ni 2＋was separated from interference elements（Cr,Fe,W,etc.）.The precipitate was dissolved in hydrochloric acid,with superfluous EDTA added,which formed the complex.With xylenol orange as the indicator,the remains of EDTA was back titrated with standard Zn2＋salt solution in HAC-NaAC buffer solution（pH=5.5-6）.The good precision of this method can meet the requirements on determination of nickel in hastelloy alloy.