Simultaneous determination of seven impurities in high-purity cobalt oxide by ICP-AES after matrix separation using 1-nitroso-2-naphthol as a precipitant

Abstract

A method was developed for the simultaneous determination of seven trace impurities (Cd, Mn, Pb, Zn, Cu, Fe and Ni) in high-purity cobalt oxide by ICP-AES. The matrix effect was eliminated by precipitation with 1-nitroso-2-naphthol. The matrix effect of cobalt on the absorptions of trace impurities, the effects of reaction time, pH value, dosage of precipitant on the formation of cobalt-1-nitroso-2-naphthol complex, the effects of hydrochloric acid on the stability of this complex and masking of elements were studied. Recoveries of the impurities in spiked sample are from 90% to 110% with a precision of 1.1%–5.0% RSD. The detection limits of the seven elements are in the range of 0.01–0.24µg/g. The method can be applied to the analysis of high-purity cobalt metal, cobalt oxide and other cobalt compounds.

Keywords

trace impurity / high-purity cobalt oxide / matrix separation / inductively coupled plasma atomic emission spectrometry (ICP-AES)