丁二酮肟沉淀分离-络合滴定法测定镍铁中镍

Determination of Nickel in Nickel Iron with Dimethylglyoxime Precipitate Separation-compleximetry

试样以稀硝酸溶解高氯酸冒烟后，酒石酸掩蔽剂将铁等干扰元素配位掩蔽，以氨水调节至刚果红试纸呈紫色后，在pH5～7的乙酸铵缓冲溶液微酸性介质中，二价镍定量地被丁二酮肟沉淀。用滤纸过滤，使镍与铁等干扰元素分离，用热盐酸将丁二酮肟沉淀溶解于原烧杯中，加入过量的EDTA标准溶液，用氨水及六次甲基四胺调节pH5～6，以二甲酚橙为指示剂，用锌标准溶液返滴定过量的EDTA。

After the sample was solved by dilute nitric acid and made to smoke by perchloric acid,the masking agent tartaric acid was used to complex and mask disturbing elements such as iron. After it was adjusted with ammonia until the test paper turned purple,in subacid medium of pH 6 - 7 ammonium acetate buffered solution, bivalent nickel was precipitated quantificationally by dimethylglyoxime. Filter paper was used to filter it to separate nickel from disturbing elements like iron,＇hot hydrochloric acid was used to solve dimethylglyoxime precipitate in the original beaker, excessive EDTA standard solution added, then ammonia and hexamethylenetetramine were used to adjust it at pH 5 6,with xylenol orange as the indicator, standard solution of zinc was used to back titrate superfluous EDTA.