Amperometric titrations with the help of selenites - Determination of cobalt

Abstract

A new procedure for rapid amperometric titration of cobalt based on precipitation of cobalt as the normal selenite is described. Potassium chloride (0.1 M) containing 0.01% gelatin as the maximum suppressor has been used as the supporting electrolyte. The use of 50% overall concentration of methanol was found essential for these titrations. The concentration of alcohol necessary for cobalt concentrations below 2 millimolars was 70%. The titrations have been performed at an applied potential of -1.5 volts vs. S.C.E. Effect of methanol on the equivalence point of the titration has also been studied. The procedure described gives accurate results, which agree well with the formula CoSeO3 for the normal selenite of cobalt. © 1961 Springer-Verlag.