Sensitive methods for the determination of trace amounts of cobalt and copper by complexation with 3-(2'-Thiazolylazo)-2,6- diaminopyridine (2,6-TADAP) are described. Copper forms a 1:2 violet complex with the reagent having a molar absorptivity of 1.00 104 L mol-1cm-1, Baer's law is obeyed over the range 0 -50.84 μg in the total volume of 10ml. Cobalt also forms a 1:1 green complex with a molar absorptivity of 1.07 104L mol-1cm-1 and obeying Beer's law over the range 0 -23.57 μg in the total volume of 10 ml. The procedure is simple and rapid without any tedious extraction steps for copper and without oxidation of cobalt (II) to cobalt (III)

Spectroscopy Letters, Volume 25, Issue 7 November 1992 , pages 1049 - 1055