DISODIUM ETHYL Bis(5-TETRAZOLYLAZO)ACETATE TRIHYDRATE COLORIMETRIC REAGENT FOR NICKEL AND COPPER

Disodium ethyl bis(5-tetrazolylazo)-acetate trihydrate forms a water- soluble, highly colored complex with nickel(II) ion that can be used for a quantitative colorimetric determination in the presence of cobalt and iron. It also forms a stable, highly colored, 1 to 1 complex with the copper(II) ion, which has a high absorbance value even at low concentration. Of the com mon cations of the first transition metal series, only cobalt(II) interferes; however, this can be eliminated by calculations using simultaneous equations. (auth)