Can serum be used in XF assay media?

It is not recommended to add serum (e.g. FBS) to the final XF assay medium because it affects medium buffering capacity and may bind non-specifically to drugs/compounds to be tested.  Further, it is not recommended to use serum in the sensor cartridge injection ports due to potential port leaks and/or injection failure. If FBS is absolutely required, a low concentration of 1-2% may be used, or empirically determined via a serum titration experiment.  Note that presence of serum in XF assay media may alter the efficacy of FCCP or drugs/compounds being tested, and thus the optimal concentration of FCCP or drugs/compounds being tested may increase in the presence of serum.