PTFE membrane is a thin, highly porous film that behaves as an absolute retentive membrane. Their inherently hydrophobic nature make PTFE membranes ideal for applications such as filtering gases, aqueous aerosols, protecting vacuum pumps, or sterile venting fermentation tanks. PTFE is inert to most chemically aggressive solvents, strong acids and bases and can be used for solvent clarification and HPLC sample prep. PTFE membranes are available unsupported and supported. PTFE membranes with a laminated polypropylene web support to one side offers improved handling characteristics. Chemical and thermal limitations are imposed by the backing.