Study on the colour reaction of cobalt with the new reagent 2,5-di(2-phenol)-1,3,4-thiadiazole

A spectrophotometric method for determination of cobalt with 2,5-di(2-phenol)-1,3,4-thiadiazole is described.In a medium of pH 7.0～9.0 cobalt reacts with 2,5-di(2-phenol)-1,3,4-thiadiazole to form a 1∶3 complex in the prescence of OB-2.The molar absorptivity is 5.74×10~4 L·mol~(-1)·cm~(-1) at 470 nm.Beer′s law is obeyed for Co in the range of 0.2～2.4 μg/mL.Trace amounts of Cobalt in VB_(12) and environmental water samples have been determined by proposed method and the results obtained are satisfactory.