There currently exists a critical and growing need for cost-effective, real-time, and in situ methods for detection of environmental pollutants such as polychlorinated biphenyls (PCBs). Herein reported is a evanescent wave Fluoroimmununosensor for measurement of PCBS. 2,4-5-Trichlorophenoxybutyric acid (TCPB) was cross linked to fluorescein ethyleneamine (TCPB-FL) and used as a optical signal generator. Protein A purified IgG, obtained from anti-PCB serum, was immobilized on quartz fibers and used as the biological recognition element in an evanescent wave fluorimeter. The optical signal was generated by the binding of the fluorescent probe TCPB-FL to the antibody (Ab)-coated fiber. Fluorescent probe concentrations in the nM range resulted in reversible binding. Several Aroclors displaced the fluorescent probe (TCPB-FL) in a concentration-dependent manner. Arochlor 1248 was detected from the ppb to ppm range. Arochlor 1242 was also measured in methanol extracts from standard reference material soils.