The Polarography of Azo Dyes

Abstract

Twenty‐one water‐soluble azo dyes– mono‐, bis‐, tris‐, and tetrakis‐azo, selected from the acid, basic, mordant, and direct dyeing classes–have been examined by polarographic methods. The object was to determine how far these methods could be used for the identification and estimation of azo dyes in general. With a few exceptions, the half‐wave potential corresponding to the reduction of azo groups does not change very greatly from one dye to another, and this quantity has therefore little value as a general means of identification. When the correct experimental conditions have been established, the polarographic method lends itself to the accurate estimation of all the dyes that have been studied.