Luminol-specific extrinsic lyoluminescence of X-ray irradiated sodium chloride

Luminol produces chemiluminescence during the dissolution of F-colored alkali halides in aqueous solutions. There seems to be an unknown excitation pathway which requires only the presence of luminol, hydrated electrons and alkaline conditions. This study was made using X-ray irradiated sodium chloride as a primary radical-generating material, which allows the simultaneous generation of hydrated electrons and highly oxidizing chlorine-containing radicals by dissolution of the irradiated solid in an aqueous solution. In alkaline solutions the reactions of chlorine-containing radicals with hydroxide ions can produce oxyradicals and hydrogen peroxide which suggest that chemiluminescence can be generated simultaneously by several pathways, and the emitting species can be either 3-aminophthalate in the case of chemiluminescence of luminol, or the luminol molecule itself, or both. However, it was clear that the dissolution-uncovered holes were the primary species responsible for initiation of most of the luminescence observed. The present method allows luminol detection below nanomolar level, and the linear logarithmic calibration range covers several orders of magnitude of concentration. Therefore, derivatives of luminol are proposed as labels in lyoluminescence bioaffinity assays.