氟化物取代EDTA滴定法快速测定铝锰镁合金中铝

Fast Determination of Aluminium in Aluminium-manganese-magnesium Alloy by Fluoride-Substitute EDTA Titrimetric method

试样以酸溶解后，采用定量的氯化钡与过量的氢氧化钠一次性沉淀分离铝锰镁合金中的锰、铁、镁干扰元素，再用氢氧化钠沉淀分离铁、镁的二次沉淀与铝分离。滤液中加过量于铝的EDTA标准溶液，调节pH。左右使铝与其它少量干扰元素配位络合物，以PAN为指示剂，用硫酸铜标准溶液滴定过量的EDTA。加氟化铵煮沸取代出与铝定量络合的EDTA，再用硫酸铜标准溶液滴定被’氟化铵配位取代的EDTA，借此测定合金中的铝量。

After samples were dissolved by acid, quantitative barium chloride and superfluous sodium hydroxide were used to totally precipitate and separate the disturbing elements in aluminium-manganese-magnesium alloy such as manganese, iron and magnesium, which separated manganese first with sextic methyl tetramine and then separated magnesium and iron secondly. Adding to EDTA standard solution with excessive aluminium in filtrate, adjusting it at pH4 to complex aluminium with a small amount of other disturbing elements,with PAN as the indicator, then use copper vitriolic standard solution to titrate excessive EDTA. Ammonium fluoride was added to make it seethe to substitute the rational EDTA complexed with aluminium, again copper vitriolic standard solution was used to titrate the EDTA displaced by ammonium fluorid,by which aluminium content in alloy was determined.