Extraction systems for the flame atomic absorption spectrometric determination of trace amounts of impurities in high-purity cobalt salts

Abstract

Various extraction systems including HCl-long-chain quaternary alkylammonium salts-ammonium pyrrolidine dithiocarbamate (APDC)-organic solvents were investigated in order to determine the optimum conditions for the extractive separation and concentration of trace amounts of Ag, Bi, Cd, Cu, Fe, Mo, Pb, Sb and Zn from high-purity CoSO₄, CoCl₂, Co(OOCCH₃)₂, CoCO₃ and Co(NO₃)₂. The best results for multi-element pre-concentration were obtained with the extraction system 2 mol l^–1 HCl-2% methyltrioctylammonium chloride-0.001 mol l^–1 APDC-isobutyl methyl ketone. This extraction system with mixed ligands permits the flame atomic absorption spectrometric determination of 5 × 10^–6% Ag, Cd and Zn, 1 × 10^–5% Fe and Pb and 5 × 10^–5% Bi, Mo and Sb in high-purity cobalt salts in a single extraction step.