The Spectrophotometric Studies on Color Reaction of 6,8-Disulfonaphthaleneazochlorosulfophenol with Niob- ium (V)

The color reaction of 6,8-disulfonaphthal eneazochlorosulfophenol with niobium (V) has been studied. The acidity for determiningniobium(V) is 0. 5～3mol/ L HCl. The molar ratio of Nb(V) to the reagent in the complex is 1:3. The complex of niobium (V) has a maximum absorption at 649 nm and the molar absorptivity is 4.42×10~4L·mol~(-1)-cm~(-1).A sensitive and selective method for the spectrophotometric determination of niobium (V) has been developed. It is applicable to determine niobium (V) in steels.