The polarography of Fast Red E

Abstract

The dye Fast Red E, 2-hydroxy-1, 1′-azonaphthalene-4′,6-disulphonic acid, disodium salt, is reduced at the dropping-mercury electrode in a single four-electron wave over the pH range 2·0–11·3, with E_½ values ranging from –0·08 to –0·61 V versus S.C.E. The rising portion of the polarographic wave is markedly influenced by the adsorption of depolariser but well defined limiting currents that are proportional to concentration in the range examined, viz., 10^–3–10^–4M, are obtained.