Cathode Ray Polarographic Microdetermination of Cobalt in Nickel and of Nickel in Cobalt

概要

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A method for the microdetermination of cobalt in nickel and nickel in cobalt by using the cathode ray polarograph, Randles type, is described. The procedure established is as follows. After dissolving samples, the majority of iron was separated from the solution by extracting it with methyl isobutyl ketone. The resulting solution was adjusted to contain 0.5M NH_4OH+0.1M NH_4Cl as supporting electrolyte. The current-voltage curves were observed on the cathode ray screen, and the peak potentials for nickel and cobalt measured in this way were -1.09 volt and -1.29 volt vs. S. C. E., respectively. This method was applied to the determinations of cobalt and nickel in standard iron samples and unknown metallic cobalt and metallic nickel samples. The results of these analyses agreed well with certificated values and with those obtained by a standardized spectrophotometric method. By using above procedure, the cathode ray polarographic determinations of more than 0.01% of nickel in metallic cobalt and more than 0.05% of cobalt in metallic nickel could be made. The concentration limit of determination of each of cobalt and nickel by this method was 0.03μg/ml (corresponding to about 5×10 mol/1).
東北大学の論文