Influence of oxidant-species scavengers on the chemiluminescence (CL) emission generated during the oxidation of pyrogallol by hydrogen peroxide

Abstract

The influence of compounds and enzymes that trap or scavenge oxygen species on the chemiluminescence (CL) emission generated by the oxidation of pyrogallol with H 2O 2 is investigated. NaN 3 was chosen for trapping singlet oxygen species, superoxide dismutase (SOD) was chosen as a scavenger of O 2 − and catalase (CAT) and peroxidase (PER) were chosen as scavengers of H 2O 2. The CL emission with H 2O 2 is limited to the pH range 10–12 with the peak intensity at pH 11.0. From the investigation, there is evidence that in the presence of PER, the pH of appearance of CL emission is decreased, while simultaneously, the level of emission is increased; this pH shift indicates the effect of PER on the rate of purpurogallin decomposition achieved through complex formation. On the other hand, CAT enhances CL emission without changing the optimum pH, suggesting its contribution to the formation of only oxygen excimers. Superoxide dismutase (SOD), on the contrary, contributes to the extinguishing of CL emission at pH 11.0 thus giving evidence of the contribution of superoxide ions to the formation of oxygen excimer species. Finally, NaN 3 enhances CL emission, suggesting a synergistic effect on pyrogallol oxidation with CL emission.