Abstract: An attenuator is included in a reagent medium of a luminescent specific-binding assay to suppress undesirable extraneous light. In one such assay, an analyte in a sample is reacted with a specific binding partner attached to a solid surface, forming an immobilized pair at the surface. One member of the immobilized pair is then allowed to react with a specific binding partner previously conjugated with one component of a luminescent reaction system, and the remaining components are provided in the reagent medium. The resulting light emitted in the luminescent reaction is recorded on photographic film or other photodetector as a measure of the presence and quantity of the analyte in the sample.

Abstract: A luminescent substrate preparation having a concentration of catalytic inhibitors of less than about 100 ppm. The preparation is obtained by heating commercial grade luminol in a basic solution, crystallizing the luminol and separating the luminol crystals from the boiled solution. The heating, crystallization and separation steps are preferably repeated sequentially at least four times, with the starting material for each sequence after the first being the luminol preparation produced in the previous sequence. The luminol preparation has an enhanced pattern of activity, in that light output is substantially constant over a period of at least about one hour, with the intensity of light emitted by the preparation being at least about ten times that of commercially available luminol. Because of these enhanced characteristics, the luminol preparation is particularly adapted for use as a tag in specific binding assays where the concentration of analyte to be detected is low.