Investigations of the Enhancer Effect of a High-Salt Concentration Medium on the Luminol Chemiluminescent Reaction

The enhancer effect of a high-salt concentration medium on the luminol chemiluminescence reaction catalyzed by either soluble or immobilized peroxidase has been investigated. Some widely used salts were tested at high concentration (up to 3 mol L): potassium chloride, sodium chloride, ammonium sulfate and calcium chloride. The magnitude of the light intensity enhancement depends on the nature of the salt and on the form of the peroxidase, i.e. free in solution or immobilized. The enhancement is observed whether the catalyst of the chemiluminescence reaction is peroxidase or ferricyanide. Both the enhanced or nonenhanced luminol chemiluminescence spectra have a maximum wavelength emission at around 425 nm. The results reported in this study are in favor of an action of the salts on the nonenzymatic steps of the luminol chemiluminescence reaction rather than a modification of the enzymatic process.