Application of cobalt ammine complexes for the simultaneous determination of traces of As, Fe, Ti, V and Zr in high-purity cobalt metal by lanthanum hydroxide coprecipitation and inductively coupled plasma-atomic emission spectrometry.

Co is not coprecipitated with lanthanum hydroxide in ammonium hydroxide solution due to the formation of soluble salts of cobalt ammine complexes. This complexation reaction has been applied to the simultaneous determination of five trace impurities (As, Fe, Ti, V and Zr) in high-purity Co metal by inductively coupled plasma-atomic emission spectrometry. Warming the solution and double coprecipitation are effective for separating the trace elements simultaneously from a large amount of cobalt ammine complexes.

Determination of traces of selenium in heat-resisting alloys by graphite-furnace atomic-absorption spectrometry after co-precipitation with arsenic.

Traces of selenium in complex nickel- and cobalt-based heat-resisting alloys have been determined by co-precipitation and graphite-furnace atomic-absorption spectrometry. The alloys are dissolved in a mixture of concentrated hydrochloric acid, concentrated hydrofluoric acid and 30% hydrogen peroxide. Selenium does not volatilize to any significant extent during the dissolution and concentration.

Determination of traces of tellurium in heat-resisting alloys by graphite-furnace atomic-absorption spectrometry after co-precipitation with arsenic.

A simple analytical method has been developed for the determination of traces of Te in complex heat-resisting alloys by graphite-furnace atomic-absorption spectrometry. Nickel-base and cobalt-base heat-resisting alloys are dissolved in concentrated hydrochloric and hydrofluoric acids plus 30% hydrogen peroxide. Tellurium is separated from the matrix by co-precipitation with As and dissolved in nitric acid.