HPLC Mobile Phase Filtration Membranes - Pall. Filter Media GH Polypro (GHP, hydrophilic polypropylene), TF (PTFE, hydrophobic polytetrafluoroethylene), PVDF (hydrophilic polyvinylidene fluoride), and Nylaflo™ (hydrophilic nylon) membranes Pore Size 0.2 and 0.45 µm Typical Thickness GHP Membrane 0.2 µm: 101 µm (4.0 mils) 0.45 µm: 114 µm (4.5 mils) TF (PTFE) Membrane 0.2 µm: 139 µm.