Abstract: A new spectrophotometric method for determination of cobalt with 2-aceto-pyridine condensation(2'-pyridine imido-group) hydrazine as coloration reagent was established.In a medium of pH 7.0~8.0,cobalt reacts with 2-aceto-pyridine condensation(2'-pyridine imido-group) hydrazine forming orange yellow complex with a molar ratio of 1∶2.In the range of 360~500 nm wavelength,this complex has bigger absorbance,the apparent molar absorption coefficient is 1.02×104 L·mol-1·cm-1 at 440 nm.Beer's law is obeyed for Co2...