Kinetics and Mechanism of Catalysis by Ferrihaems in the Chemiluminogenic Oxidation of Luminol by Hydrogen Peroxide

The kinetics of catalysis by deuteroferrihaem (deuterohaemin) were studied in the chemiluminogenic oxidation of luminol by hydrogen peroxide. The results imply that two distinct catalytic mechanisms operate to yield chemiluminescence from excited aminophthalate emitter in this system. The first mechanism involves initial one‐electron oxidation of luminol by an oxidised derivative of deuteroferrihaem with well‐established peroxidatic oxidant properties. The second mechanism involves a concerted pathway very similar to that which has been proposed [Olsson, T., L. Ewetz and A. Thore (1983), Photochem. Photobiol.38, 223–229] to explain protoferrihaem (haemin) catalysis in luminol oxidation. Deuteroferrihaem is a much more effective catalyst than protoferrihaem on a mole‐for‐mole basis and could be used with advantage in chemiluminescence analyses.