Polarographic determination of niobium in steels and nickel base alloys

Technique for direct polarographic niobium determination in alloyed steels and nickel base alloys in the presence of copper and vanadium without their preliminary separtion has been developed. The determination is performed from concentrated hydrochloric acid solutions containing sulphuric acid and polyatomic alcohol in the Nb(5) concentration range 1x10-5-4x10-3 M. Hundred-fold redundancies of Cr, Ni, Mn, Fe(2) don't affect analysis results as well as 70-, 50-, 30-, 4-, and 0.5-fold redundancies of W, Ti, Mo, V, and Cu, respectively. Relative standard deviation of Nb(5) polarographic determination constitutes 0.02-0.04