Study of the interference of iron and mercury in the determination of antimony by hydride generation atomic absorption spectrometry: use of speciation models

Abstract

The use of computerised speciation models for studying the interference of iron in the determination of antimony by hydride generation atomic absorption spectrometry is discussed. The study is performed in four different acidic media, and a value of the Fe^III to Sb^III ratio is found above which the interference is observed to depend on the acidic medium. The effect of interference is explained by the oxidation of Sb^III to Sb^V and the generation of the hydride from the higher oxidation state. A new version of the computerised speciation model application Complex gives satisfactory explanations for these differences in terms of the modifications which the potential of the Fe^III-Fe^II system undergoes. This same methodology is used to explain the absence of interference from Hg^II.