PCB Mixture 2263,12 2,2,5- Trichlorobiphenyl PCB18 1999,12 2,4,4`-Trichlorobiphenyl PCB28 2264,12 2,4,5`-Trichlorobiphenyl PCB31 2265,12 2,2`,3,5`-Tetrachlorobiphenyl P