Abstrakt

Mechanism for the release of inorganic arsenic from roxarsone, 3-nitro-4-hydroxyphenylarsonic, by cyclic voltammetry at a gold electrode

Tsanangurayi Tongesayi

Roxarsone, an arsenic-containing poultry-feed additive, is stable in fresh poultry litter but degrades to inorganic arsenic among other products when the litter is composted. Inorganic arsenic is obviously formed via the cleavage of the C-As bond but the mechanism of the cleavage of this bond remains obscure. In this work, cyclic voltammetry was used to study the redox behavior of roxarsone at a gold electrode. An oxidation peak which was absent in blanks and which could not be attributed to redox activities at the nitro and the arsonic acid groups was observed at more positive potentials. The peak appeared even when the anodic scan was initiated at potentials more positive than the peak potential for the first reduction peak indicating that it was due to the oxidation of the bulk analyte, roxarsone. This could be due to the oxidative aromatic fission of roxarsone which will subsequently lead to the cleavage of the C-As bond.