Polarographic and voltammetric investigation of 8-hydroxy-7-(4-sulfo-1-naphthylazo)-5-quinoline sulfonic acid

Abstract

The behaviour at HMDE and SMDE of 8-hydroxy-7-(4-sulfo-l-naphthylazo)-5-quinolinesulfonic acid has been studied by several techniques including Square wave voltammetry (SWV), Differential pulse plarography (DPP), Direct current polarography (DCP) and Cyclic voltarnmetry (CV). Current-potential curves recorded at HMDE and SNIDE electrode provide information on electrode reaction mechanism. The reduction of a pre-protonated azo group involving a four-electron process and two peaks or waves, gives amine derivatives in acidic solutions. In alkaline solution the reduction process occurs at more negative potential with the formation of a stable hydrazo compound. The electrochemical reduction mechanism of the azo compound is suggested using SWV, DPP, DCP and CV techniques in aqueous solutions of varying pH. (c) 2004 Elsevier Ltd. All rights reserved.