Elimination of Iron Interference on Atomic Absorption of Chromium with Air-Acetylene Flame

Abstract

The interference of iron on the absorbance of chromium and its elimination in atomic absorption spectrometry was investigated by the use of air-acetylene flame.The depression of chromium absorption was observed in the spraying of chromium (III) and iron (III) mixture, while the enhancement was observed in the spraying of chromium (VI) and iron (III) mixture. However, the addition of hydroxylamine was effective to suppress iron interference on chromium absorption, presumably resulting from the reduction of iron In to iron (II). The elimination of iron interference was completed by the addition of hydroxylamine and o-phenanthroline. Possibly the organic ligands hinder the formation of mixed oxide in the condensed phase and release the chromium directly in the vapor state before a non-volatile oxide forms.This technique of interference elimination was applied to the determination of chromium in steels successfully.