Determination of azo compounds by differential pulse voltammetry at a bismuth/poly(p-aminobenzene sulfonic acid) film electrode and application for detection in food stuffs

This paper describes the fabrication, characterization and application of a bismuth/poly (p-aminobenzene sulfonic acid) (Bi/poly(p-ABSA)) composite film-coated glassy carbon electrode for the electrochemical determination of azo compounds. This electrode was fabricated by depositing bismuth on the poly(p-ABSA) modified electrode at −0.9 V. Azo compounds such as 1-(2-pyridylazo)-2-naphthol (PAN), 4-(2-pyridylazo)-resorcinol (PAR) and azobenzene were determined on this electrode by differential pulse voltammetry. Factors influencing the determination performance including the film preparation and solution pH have been optimized. This new electrode presented well-defined, reproducible and sharp determination signals. The results confirmed that the Bi/poly(p-ABSA) electrode offered high-quality stripping performance compared with the bismuth film electrode. Under the optimum conditions, the detection limits of PAN, PAR and azobenzene were 4.1 × 10−8, 3.3 × 10−8 and 3.8 × 10−8 mol L–1, respectively. The influence of foreign substances on the signal was studied and the new electrode was successfully applicable to analysis of azo compounds in real beverage samples.