Abstract: Methods of assaying for (i) a pterin by immunoassay employing a pterin as capture agent, (ii) neopterin by chemiluminescent microparticle immunoassay (CMIA) employing an anti-neopterin antibody (Ab) as capture agent, (iii) neopterin by an immunoassay (IA) employing an acridinium (Acr)-labeled anti-neopterin Ab as conjugate, and (iv) neopterin by an IA employing Acr-labeled neopterin as tracer; an Acr-labeled anti-neopterin Ab; a conjugate/complex comprising anti-neopterin Ab and a carrier scaffold; a conjugated pterin; a conjugate comprising an Acr-labeled pterin and a carrier scaffold; an immunogen comprising neopterin and a carrier protein; a conjugate comprising such an immunogen and an Acr compound; an immunogen comprising a carrier protein and a neopterin hapten; a conjugate comprising such an immunogen and an Acr compound; a kit for assaying a pterin comprising a pterin as a capture agent and instructions for IA; and a kit for assaying neopterin comprising an anti-neopterin Ab as a capture agent and ins

Abstract: Reagents and an immunoassay for detecting the presence or amount of polychlorinated biphenyls in a test sample. The assay is performed by adding a known concentration of a tracer labeled with a detectable moiety and a known concentration of an analyte-specific antibody to a test sample to form a mixture, incubating the mixture to form labeled tracer-antibody and analyte-antibody complexes, and determining the presence or amount of tracer-antibody complexes formed as a measure of the presence or amount of analyte in the test sample. Reagents provided include tracers, immunogens and an additive compound useful in preventing non-specific binding of the polychlorinated biphenyls to proteins which may be present in the test sample. A kit for performing the assay also is provided.