AUTOMATIC-DETERMINATION OF COBALT AT THE SUBMICROGRAM PER MILLILITER LEVEL USING A FLOWTHROUGH SPECTROPHOTOMETRIC SENSOR

A flowthrough spectrophotometric sensor for the determination of cobal t at the nanogram per millilitre level using pyridoxal 4-phenylthiosem icarbazone 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 m u g ml(-1) respectively, and a linear range of at least 0.04-18 mu g m l(-1). The method is subject to very few interferences because the str ongly acidic medium used prevents the formation of most complexes of t he reagent with other metal ions. The method was applied to the determ ination of cobalt in pharmaceutical preparations.