二溴对甲基偶氮羧褪色光度法测定铬(Ⅵ)

Spectrophotometric Determination of Trace Chromium (Ⅵ) with Dibromomethyl Carboxyazo

研究了新显色剂二溴对甲基偶氮羧与Ｃｒ２Ｏ２－的褪色反应。发现它们在硝酸介质中具有高灵敏的褪色反应，Ｃｒ（Ⅵ）量在 ０～１６０μｇ／Ｌ内符合比耳定律．摩尔吸光系数为 １．２ ×１０ ５Ｌ·ｍｏｌ－１·ｃｍ－１。据此建立了一种新的测定Ｃｒ（Ⅵ）的光度法。

The fading reaction of dibromomethyl carboxyazo with Cr2 O2- was studied. In the medium of nitric acid, the reaction has high sensibility. The Beer's law is obeyed in the range of 0-160 μg/L Cr(Ⅵ), and the molar absorptivity of reaction is 1.2 × 105 L·mol-1·cm-1. The method has been used for determining trace chromium in alloy steel and water.