VOLTAMMETRIC STUDY OF THE EXTRACTANT 4-METHYL-N-QUINOLIN-8-YLBENZENESULFONAMIDE AT A CARBON-PASTE ELECTRODE

An electroanalytical study of 4-methyl-N-quinolin-8-ylbenzenesulfonami de, a model compound of similar structure to that of the active compon ent in the commercial extractant LIX 34, at a carbon paste electrode, has been carried out using different voltammetric techniques. The comp ound was oxidized in methanolic medium (methanol-H2O, 20 + 80), with B ritton-Robinson buffers as supporting electrolytes and KCl solution (i onic strength 1 mol l(-1)), giving rise to a voltammetric peak in the pH range 1.2-12.0. The effect of pH on the anodic voltammograms has be en studied and the graph of E(p) versus pH shows two straight lines in tercepting at a pH value of 9.6. The oxidation process for the compoun d is irreversible (<(alpha n)over bar> = 0.63) and predominantly diffu sion controlled, although with an important adsorptive component. The electrode process can be attributed to the oxidation of the sulfonamid e group. A voltammetric method for the determination of the compound h as been developed and has been applied to samples of LIX 34.