【摘要】 <正> 不对称的偶氮氯膦类试剂与稀土有灵敏的显色反应,近几年来我国分析工作者对其做了不少工作,筛选出一些具有实用价值的显色剂。纵观前面的工作,都是在较强的酸性条件下(pH1左右)进行的研究。为了进一步了解这类试剂的作用,本文选用弱酸介质(pH～4.5)对10种不对称的偶氮氯膦类试剂与稀土的反应做了研究。发现,对氯偶氮氯膦与钇有一特殊的β型反应,形成络合物的最大吸收波长为746 nm,摩尔吸光率为1.56×10~5升·更多还原

【Abstract】 The color reactions between yttrium and the bisazo derivatives of chromotropic acid have been studied. It has been shown that among these reagents chlorophosphonazo-p-Cl（CPA-p-Cl）gives the most sensitive reaction with yttrium in pH 4.5 HAc-NaAc medium.The method of synthesis of CPA-p-Cl and the conditions of its color reaction with yttrium have been investigated. CPA-p-Cl forms a β-type complex with yttrium in pH 4.5 HAc-NaAc medium, having a maximum absorption at 746 nm with an apparent molar absorptivity of 1.56×10^l mol^-1·cm^-1. At room temperature, the complex is formed in 30 min. and its absorbance remains stable for at least 24 hr. Beer’s law is obeyed for 3～14 μg of yttrium in 25 ml of solution. Ten parallel determinations of 10 μg yttrium gave a coefficient of variation of 0.8%. Using lactic acid as the masking reagent, yttrium is determined in the presence of the same amount of lanthanum or cerium with a relative error smaller than 5%.更多还原