The potentiometric microdetermination of cobalt in organic compounds after combustion in a modified oxygen flask

Abstract

A reliable method for the microdetermination of cobalt in organic cobalt compounds is described. The sample is combusted in a modified oxygen flask and the products are absorbed in 6 M HC1. The Pt basket is then boiled in the absorption solution and the sparingly soluble residue of cobalt oxides is completely dissolved. After cooling, the solution is transferred to a titration cell and neutralized with NaOH in the presence of methyl red. After careful adjustment of the pH, the Co(II) is finally determined in a buffered 60% ( v v ) dimethylformamide solution by potentiometric titration with 0.033 M sodium diethyldithiocarbamate solution. The results obtained are accurate within ±0.08%; the recoveries of Co are in the range of 99.52 to 99.97%; the standard deviation is 0.06%. The potentiometric titration of Co(II) with sodium diethyldithiocarbamate and other reagents, as well as the conditions for the oxygen flask combustion of organic cobalt compounds, is discussed.