关键词: 比色法, 萃取剂, 显色剂, 脂肪酸, 萃取, 稀土元素, 偶氮胂III, 锡矿物, 丁酸

The extraction behaviour of rare earth ions form saturated ammonium nitrate solution at pH4.0-5.5 with n-butyric acid has been investigated systematically. Arsen zo III froms a colored complex of \l\max. 660mn with rare earth ions in acidic solution. In this determination tin ion is masked by the addition of Zn-EDTA solution and a mean standard deviation of 0.0007-0.0014% was obtained. Actual analysis shows that the selectivity of this method is high and the method has been successfully applied to the determination of microamount of rare earth ions in the concentrated tin ores with satisfactory results.

Key words: COLORIMETRIC METHOD, EXTRACTIVE AGENT, COLOUR REAGENTS, FATTY ACID, EXTRACTION, RARE ELEMENT, ARSENZO III, TIN MINERAL, BUTANOIC ACID