PTFE syringe filters are made of Polytetrafluoroethylene (PTFE) membrane and a polypropylene overmold housing. Available in 13 mm and 25 mm diameters and 0.22 μm and 0.45 μm pore sizes. PTFE is the membrane of choice for use with aggressive solvents, liquids, and gases that can attack other membranes It is resistant to most acids, alkalis, and solvents. PTFE membranes are particularly suitable for preparing samples for HPLC analysis. The hydrophobic nature of the membrane also has applications for air and gas sterilization.