Flow injection analysis with chemiluminescence detection in the determination of fluorescein- and fluorescamine-labelled species

Many fluorescence immunoassays have indifferent limits of detection because of the background signals from biological samples. Scattered light contributes to this background, but can be eliminated by exciting conventional fluorescent labels via chemiluminescence reactions involving bis(2,4,6-trichlorophenyl)oxalate. This reaction, whose rate can be controlled, is conveniently used in a flow injection system with a luminometer as a detector. Such a system is applied to study fluorescein- and fluorescamine-labelled species at concentrations as low as 10^?11 M (ca. 0.5 pg in a 100 μl sample). The effects of antibodies on the luminescence signals from labelled antigens are discussed.