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钼在盐酸羟胺(Hy)存在下,与EDTA络合形成浅黄色络合物,已应用于钼铁,钨钼合金中钼的测定,系在pH2络合,二甲酚橙作指示剂,铋盐返滴定。Lassner用环已二胺四乙酸(DCTA)作络合剂使形成Mo~(6+)-Hy-DCTA三元络合物。pribil推荐络合物形成的pH=4.5。本文通过试验得出三元络合物形成的最佳条件是pH4.5的乙酸-乙酸钠缓冲溶液,煮沸20分钟以上形成完全,再以六次甲基四胺调正pH至5.5～6,以5-Br-PADAP(5-溴-吡啶偶氮-二乙氨基苯酚)为指示剂,邻二氮菲为辅助指示剂,铜盐返滴定,可用于2～60毫克钼量的测定。通过一次碱分离,用此法测定了铁、镍基合金中10～70%的钼。相对标准偏差0.33～0.61%。
Molybdenum complexed with EDTA to form a light yellow complex in the presence of hydroxylamine Hy (Hy) has been used in the determination of molybdenum in ferromolybdenum and tungsten-molybdenum alloys, complexed at pH 2 with xylenol orange as an indicator, bismuth Salt back titration. Lassner cyclohexane diamine tetraacetic acid (DCTA) as a complexing agent to form Mo ~ (6 +) - Hy-DCTA ternary complex. pribil Recommended Complex Formation pH = 4.5. The best conditions for the formation of ternary complex were found in this paper. The optimum conditions for the formation of the ternary complex were pH 4.5 acetic acid-sodium acetate buffer solution. After boiled for more than 20 minutes, the pH value was adjusted to 5.5-6 with hexamethylenetetramine. Using 5-Br-PADAP (5-bromo-pyridylazo-diethylaminophenol) as an indicator and phenanthroline as an auxiliary indicator, the copper salts were back-titrated and could be used for the determination of molybdenum content from 2 to 60 mg. By an alkaline separation, this method was used to determine 10-70% molybdenum in iron and nickel-based alloys. The relative standard deviation was 0.33 ~ 0.61%.