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众所周知,许多不对称变色酸双偶氮胂(膦)型衍生物,对稀土、钍、钪、铋、铬、碱土等金属离子具有优良的分析性能,并已广泛应用于实际样品的测定。对乙氧基二溴偶氮胂,化学名称为2-(2-胂酸苯偶氮)-7-(2,6-二溴-4-乙氧基苯偶氮)-1,8-二羟基萘-3,6-二磺酸,是我们最近合成的新稀土显色剂。酸度较低(0.2mol·L~(-1)盐酸)时,试剂与所有稀土元素形成灵敏的蓝色配合物,有利于稀土总量测定的实际应用。随着酸度的提高,试剂与铈组稀土仍能发生灵敏的显色反应,而钇组稀士配合物的吸光度则逐渐降低。本文较系统的研究了高酸度(2mol·L~(-1)盐酸)下,试剂与铈组稀土的显色反应,其特点是:灵敏度高(ε_(La)=1.17×10~5,ε_(Ce)=1.18×10~5,ε_(pr)=1.28×10~5,ε_(Nd)=
It is well-known that many asymmetric chromotropic acid bis (arsenazo) derivatives have excellent analytical performance on rare earth, thorium, scandium, bismuth, chromium and alkaline earth metal ions and have been widely used in the determination of actual samples. P-Ethoxy dibromoarsenazone, with the chemical name 2- (2-arsonatphenylazo) -7- (2,6-dibromo-4-ethoxyphenylazo) -1,8-di Hydroxynaphthalene-3,6-disulfonic acid, is our recently synthesized new rare earth color reagent. When the acidity is low (0.2 mol·L -1 hydrochloric acid), the reagent forms a sensitive blue complex with all the rare earth elements, which is in favor of the practical application of the determination of the total rare earth content. With the increase of acidity, the reagents and rare earths of cerium group can still react sensitively, while the absorbance of the rare earth complexes of yttrium group decreases gradually. In this paper, the chromogenic reaction of rare earth with cerium was studied systematically under high acidity (2 mol·L -1 hydrochloric acid). The characteristics of the reaction were: high sensitivity (ε La = 1.17 × 10 -5, ε_ (Ce) = 1.18 × 10 -5, ε pr = 1.28 × 10 -5, ε Nd =