Hello Chris,
Some info here. See: https://dx.doi.org/10.1021/acs.jproteome.8b00831
Baud et al., “An Optimized Method for the Proteomic Analysis of Low Volumes of
Cell Culture Media and the Secretome: The Application and the Demonstration of
Altered Protein Expression in iPSC-Derived Neuronal Cell Lines from Parkinson’s
Disease Patients.”
For our own purposes, we simply rinse cells 3x with cold PBS and move on with a
proteomics workflow. The above paper has some interesting observations that
indicate culture medium proteins continue to be released from the cells over
time.