VOLTAMMETRIC DETERMINATION OF TRACES OF COBALT(II) WITH A CHEMICALLY MODIFIED CARBON PASTE ELECTRODE

A new preconcentration and voltammetric determination method for cobalt(II) in aqueous solution with a chemically modified electrode is proposed. The accumulation behaviour and voltammetry of cobalt(II) has been investigated with a carbon paste electrode modified with cation-exchanger and 1,10-phenanthroline. The electrochemical response is characterized with respect to carbon paste composition, pH, preconcentration time, cobalt(II) concentration and other variables. For a 3-min preconcentration time, the electrode gives good linearity for 1 x 10(-7) to 4 x 10(-6) mol/l Co(II), a detection limit of 8 x 10(-8) mol/l. The response can be reproduced with a 4.0% relative standard deviation. The method is fairly free from many coexisting ions interferences. A rapid and convenient renewal procedure allows the use of a single electrode in multiple analytical determinations over several days. Satisfactory results are obtained for the determination of cobalt in a variety of certified standard reference materials.