Cathodic Electrogenerated Chemiluminescence of Luminol at Disposable Oxide-Covered Aluminum Electrodes

Abstract

Luminol exhibits strong electrogenerated chemiluminescence during cathodic pulse polarization of oxide-covered aluminum electrodes in aqueous solution. This electrogenerated chemiluminescence can be enhanced by the presence of dissolved oxygen or by the addition of other coreactants such as hydrogen peroxide, peroxydisulfate, or peroxydiphosphate ions. However, luminol detection is most sensitive in the presence of azide ions, which not only enhance the electrogenerated chemiluminescence intensity but also decrease the intrinsic electroluminescence of the thin aluminum oxide film on the electrodes mainly producing the blank emission. The present method is based on tunnel emission of hot electrons into an aqueous electrolyte solution and allows the detection of luminol, isoluminol, and its derivatives below nanomolar concentration levels. The linear logarithmic calibration range covers several orders of magnitude of concentration of luminol or N-(6-aminohexyl)-N-ethylisoluminol. Therefore, the above-mentio...