A kit containing a chemiluminescent detection system for a specific analyte, the kit comprising: (a) a first composition comprising a singlet-oxygen activatable chemiluminescent compound and a first antibody or binding fragment thereof associated therewith, wherein the first antibody or binding fragment thereof is a detection antibody that specifically binds to a first epitope of the analyte whereby the singlet-oxygen activatable chemiluminescent compound is capable of indirectly binding to the analyte via the first antibody or binding fragment thereof; (b) a second composition comprising a singlet-oxygen activatable chemiluminescent compound and a second antibody or binding fragment thereof associated therewith, wherein the second antibody or binding fragment thereof is a detection antibody that specifically binds to a second epitope of the analyte whereby the singlet-oxygen activatable chemiluminescent compound is capable of indirectly binding to the analyte via the second antibody or binding fragment thereof, and wherein the first and second epitopes at least partially overlap such that the first and second antibodies or binding fragments thereof cannot both bind to a single analyte molecule; and (c) a third composition comprising a third antibody or binding fragment thereof, the third antibody or binding fragment thereof being a capture antibody that specifically binds to a third epitope of the analyte that does not overlap with the first and second epitopes, whereby a single analyte molecule can bind the third antibody or binding fragment thereof and one of the first and second antibodies or binding fragments thereof, and wherein the third antibody or binding fragment thereof is capable of association with a sensitizer capable of generating singlet oxygen in its excited state, whereby association of the third antibody or binding fragment thereof with the sensitizer allows for the indirect binding of the sensitizer to the analyte, and further comprising the sensitizer, wherein the first antibody or binding fragment and the second antibody or binding fragment exhibit different affinities for the analyte, one of the two antibodies or binding fragment have a lower affinity for the analyte, while the other antibody or binding fragment has a higher affinity for the analyte. (a) a first composition comprising a singlet-oxygen activatable chemiluminescent compound and a first antibody or binding fragment thereof associated therewith, wherein the first antibody or binding fragment thereof is a detection antibody that specifically binds to a first epitope of the analyte whereby the singlet-oxygen activatable chemiluminescent compound is capable of indirectly binding to the analyte via the first antibody or binding fragment thereof; (b) a second composition comprising a singlet-oxygen activatable chemiluminescent compound and a second antibody or binding fragment thereof associated therewith, wherein the second antibody or binding fragment thereof is a detection antibody that specifically binds to a second epitope of the analyte whereby the singlet-oxygen activatable chemiluminescent compound is capable of indirectly binding to the analyte via the second antibody or binding fragment thereof, and wherein the first and second epitopes at least partially overlap such that the first and second antibodies or binding fragments thereof cannot both bind to a single analyte molecule; and (c) a third composition comprising a third antibody or binding fragment thereof, the third antibody or binding fragment thereof being a capture antibody that specifically binds to a third epitope of the analyte that does not overlap with the first and second epitopes, whereby a single analyte molecule can bind the third antibody or binding fragment thereof and one of the first and second antibodies or binding fragments thereof, and wherein the third antibody or binding fragment thereof is capable of association with a sensitizer capable of generating singlet oxygen in its excited state, whereby association of the third antibody or binding fragment thereof with the sensitizer allows for the indirect binding of the sensitizer to the analyte,