Automatic determination of cobalt at the submicrogram per millilitre level using a flowthrough spectrophotometric sensor

A flowthrough spectrophotometric sensor for the determination of cobalt at the nanogram per millilitre level using pyridoxal 4-phenylthiosemicarbazone as reagent and integrated preconcentration and detection in the flow cell is proposed. The method is highly selective for cobalt(II); it features detection and determination limits of 0.02 and 0.06 mu g ml(-1) respectively, and a linear range of at least 0.04-18 mu g ml(-1). The method is subject to very few interferences because the strongly acidic medium used prevents the formation of most complexes of the reagent with other metal ions. The method was applied to the determination of cobalt in pharmaceutical preparations.