What is fouling?
Lipids, sticky (hydrophobic) proteins, and nucleic acids all tend to adsorb to the skin of many UF membranes, also reducing flow rate and passage of molecules slightly smaller than the pores. Reduction in the flow rate of clean lab water following concentration of a protein solution, compared to initial water flow rate, is evidence of fouling of the membrane. Ultrafiltered lab water such as MilliQ Biocel does not have colloids which can also foul and slow down many UF membranes.
