The separation and determination of Cobalt(II) and Cobalt(III)

Abstract

A method for the seperation and determination of cobalt(II) and (III) has been developed. The acetylacetonate complexes of cobalt are utilized for the seperation, and analytical measurements are made by atomic absorption or visible absorption spetrophotometry. The sample is reacted with hot acetylacetone and diluted with 20% acetic acid. The cobalt (III) complex is seperated by extraction with benzene. The benzene layer is then diluted with n-pentanol and the cobalt(III) concentration is determined by atomic absorption spectrophotometry. The cobalt(II) concentration can be determined in the 20% acetic acid layer by atomic absorption. In the absence of other metals which form colored acetylacetonate complexes, the cobalt(III) concentration can be determined by the visible absorption spectrophotometry directly on the 20% acetic acid solution. The total cobalt concentration can be determined by any acceptable method for cobalt and the cobalt(II) concentration then obtained by the difference.