新显色剂偶氮胂DBF分光光度法测定稀土元素研究

变色酸双偶氮胂类化合物是光度法测定稀土元素的重要显色剂,如偶氮胂Ⅲ、三溴偶氮胂等。为研究各种取代基对这类显色剂与稀土配合物的影响,将对甲基二溴偶氮胂中的甲基换为甲酰基,合成得偶氮胂DBF,化学命名为2-(2-胂酸基苯偶氮)-7-(2,6二溴-4-甲酰基苯偶氮)-1,8-二羟基萘-3,6-二磺酸。

New Chromogenic Reagent Arsenazo DBF Used for Spectrophotometric Determination of Rare Earth Elements

The present paper reports the synthesis of arsenazo DBF, its characteristic, its reaction with rare earths ions and its application to the selective determination of cerium-group in aluminium-alloy. Arsenazo DBF, 2-(2-arsonophenylazo)-7-( 2, 6-dibromo-4-formylphenylazo )-1,8-dihydroxynaphthalene-3,6-disulfonic acid reacts with cerium-group rare earths to form blue-green colour complexes in NaAe-HCl aqueous solution at pH 2.2.The absorptive peak is at 630 nm. The molar absorptivity of La complexe is 1.3×10⁵ L·mol^-1·cm^-1. Beer's law is obeyed over the concentration range 0～12μg/25mL of La.