Application Note 20573. Polychlorinated biphenyls (PCBs) are man-made organic compounds composed of two phenyl (benzene ring) groups with multiple chlorine atoms attached. The heat-resistant and non-conductive properties of PCBs led to their extensive use as coolants and lubricants in electrical equipment until the late 1970s when their toxicity was recognized and their usage restricted. However, PCBs are very persistent environmental contaminants. Improper disposal and storage of old electrical equipment continue to allow the chemicals to leach into the environment. Soil and water samples are routinely tested for the presence of PCBs, and a number of EPA methods exist for their analysis. 1,2 This HPLC method shows the use of the Accucore C18 column for the separation of PCBs in a commercial mixture. The 20 minute analysis time provides good resolution between all components.