How to choose the right membrane filter for your application

1. Start with chemical compatibility (material)

Before anything else, the membrane has to survive contact with your sample. Aqueous and biological samples generally pair well with PES; aggressive solvents call for PTFE; nylon suits many organic solvents but can bind some polar compounds. See our PTFE vs. nylon vs. PES vs. PVDF comparison for the full breakdown. Get this wrong and nothing else about the filter matters.

2. Decide what you're actually trying to retain (pore size)

State the actual requirement—sterilizing (0.1–0.22 µm), general clarification (0.45 µm), or coarse particulate removal (0.8 µm+)—before picking a number. See our pore size and diameter guide for common conventions.

3. Match diameter to volume and hardware

Small syringe formats (4–25mm) suit small volumes; larger vacuum formats (47mm+) suit bulk volumes and faster processing. See our filter diameter guide for how to size this correctly.

4. Confirm sterility requirements last

Sterile filters cost more—only pay for it when your downstream use genuinely requires it (cell culture, sterile process fluids). See our sterile vs. non-sterile guide for how to decide.

Putting it together

A worked example: filtering a cell culture buffer before it goes into a bioreactor. Material: PES (aqueous, low binding). Pore size: 0.22 µm (sterilizing grade). Diameter: sized to your batch volume. Sterility: yes, required. Four decisions, in order, and you've specified the filter.