Determination of trace amounts of copper in niobium and tantalum by atomic-absorption spectroscopy

Abstract

Copper may be determined in niobium and tantalum at the 1 to 10 p.p.m. level by extraction of copper 8-hydroxyquinolinate from a fluoride medium into ethyl acetate at pH 4·5, and by direct atomic-absorption spectroscopy of the extract in an air-propane or air-acetylene flame at 3247 Å. Optimum conditions of pH, reagent concentration and solvent composition have been established, and a study of the effect of other cations and anions is presented. Only titanium(IV) and molybdenum(VI) cause interference when present in 100-fold excesses, but even these may be masked by the addition of hydrogen peroxide.