Picolinaldehyde 4-phenyl-3-thiosemicarbazone as a spectrophotometric reagent for the selective determination of small amounts of cobalt in the presence of iron

The characteristics and analytical applications of picolinaldehyde 4-phenyl-3-thiosemicarbazone are described. This compound gives coloured reactions with cobalt(II), iron(II) and (III), nickel(II), copper(II), palladium(II) and other ions, that are much more sensitive than those with picolinaldehyde thiosemicarbazone. The 1:2 yellow cobalt(II) complex has been used for the spectrophotometric determination of cobalt in the presence of iron, and applied to steel analysis.