Cobalt Determination of Cemented Carbide by Spectrophotometry with Picramazochrom as the Chromogenic Reagent

The chromogenic reaction between picramazochrom and cobalt was studied with picramazochrom as the chromogenic reagent.In the ammonium citrate-ammonia solution of pH10.0,cobalt reacted with picramazochrom to form a green complex,which exhibited the maximum Absorption wavelength at 670 nm with an apparent molar Absorptivity of 2.62×104 L/(mol·cm).And Beer's law was obeyed in the range of 0~50 μg/25 mL cobalt.When the cobalt content in cemented carbide was determined directly by the spectrophotometry with picramazochrom,the relative standard deviation was between 1.4% and 2.1%.