速差动力分析法同时测定镨、铒混合物中单一稀土

RATE DIFFERENTIAL KINETIC METHOD FOR SIMULTANEOUS DETERMINATION OF PRASEODYMIUM AND ERBIUM IN A BINARY MIXTURE

稀土元素与DBC[2-(2-肺酸基苯偶氮)-7-(2,6-二溴-4-氯苯偶氮)-1,8-二羟基-3,6-二磺酸萘,简称DBC或DBC偶氮胂]反应速率常数随着原子序数的增大而减小,所以Pr、Er之间速率常数差别大。在0.24mol/L HCl介质中Pr与DBC一混合反应即达到平衡,而铒与该试剂反应的半衰期为36秒。利用此反应,本文提出用线性外推法同时测定Pr、Er混合物中的单一稀土,推导了测量方程,用线性外推法测量了5个Pr、Er混合物试样,方法准确度约为5％。此方法简便,并不需要进行复杂的计算。

The reaction rate constants of rare earth elements with DBC [2-(2-arsenophenylazo)-7-(2, 6-dibromo-4-chlorophenylazo)-1, 8-dihydroxynaphthalene-3, 6-disulfonic acid] decrease as their atomic numbers increase. So there is a largely difference in the rate constants between Pr and Er. As soon as Pr and DBC is mixed in 0.24 mol/L HCl medium the reaction reaches equilibrium. While the half-life of the reaction of Er with DBC is 36 sec. A linear extrapolation method is proved for simultaneous determination of Pr and Er in their mixture using this reaction. The determination equation is deduced. Five samples of Pr and Er mixture have been determined by the linear extrapolation method with accuracy of about 5％. The method is simple and needs no complicated calculation.