Patent ID: 8916341

Claim:
An assay for detecting an analyte in a fluid sample, the assay comprising the steps of: a) binding the analyte to a first entity having an affinity to the analyte, said entity labeled with a photosensitizer or an enzyme to catalyze producing of said photosensitizer; b) adding to a mixture of said analyte and said entity a substrate for a photochemical reaction, said substrate is capable to be converted to a product of the photochemical reaction when said mixture of said entity, said analyte and said substrate is irradiated with a light at a wavelength within a light absorption spectrum of said photosensitizer; c) adding a reagent solution containing an additive selected from a group consisting of ascorbic acid, glycerol, and an ascorbic acid derivative selected from the group comprising ascorbate, iso-ascorbic acid, iso-ascorbate, an ascorbic acid palmitate, an ascorbic acid stearate, an iso-ascorbic acid palmitate, and an iso-ascorbic stearate; d) conducting the photochemical reaction by irradiating the mixture of step (c) with said light; and e) detecting the analyte by measuring an optical signal corresponding to the amount of the product of the photochemical reaction.