Indirect flow injection voltammetric determination of aromatic amines by monitoring at a glassy carbon electrode the excess of nitrite remaining after their diazotisation

Abstract

Excess of nitrite, after reaction with aniline, sulphanilic acid or sulphanil-amide in the presence of potassium bromide, is determined by flow injection voltammetry at a glassy carbon electrode by injection of the reaction mixture into 0.3 M hydrochloric acid. The reaction is stoicheiometric but the amperometric signal is not directly proportional to the amine concentration. For the determination of these amines (1 × 10^–6–1 × 10^–4M) the use of a 10–90% excess of nitrite is recommended. The amines have also been determined by direct injection of amine (1 × 10^–8–1 × 10^–4M) in 3.2 M hydrochloric acid into a neutral eluent 1 × 10^–4, 1 × 10^–5 or 1 × 10^–6M in nitrite and 20%m/V in potassium bromide. The reaction was incomplete in this direct injection but good reproducibility was obtained.