偶氮氯膦Ⅲ吸光光度法测定轻、重稀土元素和钇

SPECTROPHOTOMETRIC DETERMINATION OF LIGHTER AND HEAVIER RARE EARTHS AND YTTRIUM BY USING CHLOROPHOSPHONAZO-Ⅲ

本文研究了稀土元素与偶氮氯膦Ⅲ的α型及β型显色反应。在一定条件下,重稀土元素(Gd—Lu)同偶氮氯膦Ⅲ螯合物可由α型转变成β型,其中钇的螯合物转成β型倾向最大,而轻稀土元素在相同条件下仅形成α型,利用Zn-EDTA和Zn-CyDTA的掩蔽效应,可扩大显色反应的差异性。提出了在HCl-NaAc介质中分别测定轻、重稀土元素及钇的方法:在pH2.9一3.4范围内,用Zn-CyDTA作掩蔽剂,可在重稀土存在下测定轻稀土元素。在pH1.8—2.4和pH2.8—3.6,用Zn-EDTA、NaF或NaF作掩蔽剂可分别测定钇及重稀土元素。

The color reac ti ons of α-t ype and β-type of rare ear ths with chloro-phosphonazo Ⅲ have been studied in this paper.Under a certain experimental condition,α-type of heavier rare earths(Gd to Lu)chelates of chlorophosphonazo Ⅲ can be converted to β-type.The tendency of the conversion of chelates of yttrium is the largest.The corresponding chelates of lighter rare ear ths(La to Eu)do not convert to β-type under the same condition.Masking effect of Zn-EDTA and Zn-CyDTA can be utilized to enlarge the difference of color reactions.A method for spectrophotometric determination of lighter and heavier rare earths,and yttrium in HCl-NaAc buffer sol ution has been sugges ted.Ligh ter rare ear ths can be determined in the presence of heavier rare earths at 684nm,pH 2.9-3.4,using Zn-CyDTA as the masking agent.Heavier rare ear ths and yttrium can be determined respectively in the presence of lighter rare earths at 740nm in the range of pH2.8-3.6 and pH1.8-2.4,using Zn-EDTA+NaF and NaF as a masking agent respectively.