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Developed
in the early 1900's, Polychlorinated biphenyls (PCBs) are
chlorinated oils that remain stable when subjected to heat
and pressure. These traits, combined with their high electrical
resistance, made them ideal for use in insulators, transformers
and capacitors. PCBs performed well in those initial applications
and their use expanded into hydraulic fluids, casting wax,
carbonless carbon paper, compressors, pigments, adhesives
and fluorescent light ballasts.
Polychlorinated biphenyls make up a group of 209 individual
chlorinated biphenyl rings know as congeners. A PCB is typically a
mixture of 60 to 90 congeners. As the number of chlorines in a PCB
mixture increases the flash point rises and it becomes less
biodegradable.
Once in the
environment, PCBs tend to concentrate, or bioaccumulate, in animals
at the top of the food chain.
For a copy of EPA Method 1668A, click here
To
download a copy of a Horizon Technology Application Note
on EPA Method 1668A, click here.
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