Accurate Determination of Cobalt in South African Primary and Secondary Geochemical Reference Materials by Cation Exchange Chromatography and Atomic Absorption Spectrometry

Cobalt in the six S.A. primary (NIMROCS) and fourteen secondary reference samples as well as in a phosphate rock has been determined accurately by means of atomic absorption spectrometry. A selective and quantitative ion exchange separation procedure, using a 20 g column of AG50W-X8 cation exchange resin and 0.4 M hydrochloric acid-86% acetone and 1 M hydrochloric acid-80% acetone as eluting agents, is employed for the separation of cobalt from all other elements. The accuracy and precision of the described method are demonstrated by the analysis of synthetic rock solutions containing various amounts of cobalt. Amounts of 1, 10 and 100 μg of cobalt can be determined with a coefficient of variation of 1%, 0.3% and 0.2%. respectively.