This paper reports the synthesis and spectroscopic properties of all the mono-, di-, tri-, tetra-, penta-, hexa- and heptachlorobiphenyls and completes the synthesis of all 209 polychlorinated biphenyls (PCBs). The retention times and molar response factors of the 209 PCBs were determined relative to a reference standard, octachloronaphthalene. The retention times for these compounds generally increased with increasing chlorine content, and it was apparent that within a series of isomers there was an increase in retention time with increasing meta and para and decreasing ortho substitution. By use of a 50-m narrow bore fused silica capillary column coated with SE-54, it was possible to separate 187 PCB congeners, and only 11 pairs of compounds were not fully resolved. With some additional analytical improvements, isomer-specific PCB analysis can be utilized to determine the composition of commercial PCBs and accurately follow the fate and distribution of these pollutants within the global ecosystem. (Copyright (c) American Chemical Society 1984.)