The in vitro recovery of cOFM assesses the adsorption of the substance of interest to the cOFM system. In vitro recovery tests should be done with the same system components that are used in the in vivo setup (cOFM probe type, tubing sets, etc.). Once the adsorption is assessed, in vitro recovery can be used as a correction factor for in vivo results. In vitro recovery cannot be used as an in vivo recovery surrogate.