Removal of interference by chlorides in the determination of indium by graphite furnace AAS

Abstract

A method for removal of interference by chlorides in the determination of indium by graphite furnace AAS was investigated. The mixture of ammonium salt of EDTA, nickel nitrate and aluminium nitrate was suitable as a matrix modifier. Since the analyte and the other cations were masked by EDTA, the formation of indium chloride in drying step was prevented and the volatile ammonium chloride formed could be easily removed from the furnace in pre-atomization steps. On the other hand, EDTA complexes of nickel and aluminium act as sensitivity enhancement agent for the atomic absorption of indium. In the presence of 5 × 10−2 M diammonium-EDTA, 0.3 M ammonia, 4×10−3M nickel nitrate and 1 × 10−3 M aluminium nitrate, the tolerance concentration of coexisting metallic chlorides were about 400~1000 times larger than that resulted in the absence of EDTA. Furthermore, the sensitivity of indium in the atomic absorption was increased by a factor of about 20 compared to that resulted in the absence of the matrix modifier. © 1990, The Japan Society for Analytical Chemistry. All rights reserved.