新显色剂间羧基偶氮苦胺酸光度法测定铌的研究——钢铁中微量铌的测定

Spectrophotometric Determination of Niobium in Steels with a New Chromogenic Reagent Picramazochrom-m-COOH

本文研究了间羧基偶氮苦胺酸与铌的显色反应,在硝酸介质中,试剂与铌形成1∶1的蓝色配合物,在639nm波长处具有最大吸收,对比度为70nm,摩尔吸光系数为3.74×10~4,铌量在0～40μg/25mL范围内符合比尔定律。试剂用于钢铁中微量铌的测定,结果令人满意。

In this paper, the color reaction between picramazochrom-m—COOH and niobium has been studied. In nitric acid medium, niobium reacts with picramazochromm-COOH to form a 1:1 blue complex having an absorption maximum at 639nm(Δλ=70nm) with an apparent absorptivity of 3.74×10~4L·mol^(-1)·cm^(-1). Beer's law is obeyed for 0～40μg of niobium in 25mL of solution. The present method has been applied to the direct determination of niobium in steels and the results are satisfactory.