Several legacy PFAS compounds are found as a mixture of branched isomers in the environment. Restek utilizes “br” to represent “branched” for legacy PFAS compounds. A compound denoted as “br” means at least 10% of its isomeric composition is nonlinear.
Example of linear and branched PFOS:

We do not add a designation to non-legacy PFAS compounds. These compounds are linear only unless otherwise noted.

