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Filtration
Syringe filters, bottle-top filters, membrane discs and filtration systems for sterilization, clarification and particle removal.
Sterile and non-sterile options in PES, PVDF, nylon, PTFE, cellulose acetate and MCE.
Choosing a membrane
- PES — fast flow, very low protein binding. First choice for cell culture media and buffers.
- PVDF — low binding, broad chemical compatibility. Good for protein solutions and HPLC.
- Nylon — hydrophilic, robust, but binds protein. Suits solvents and mobile phases, not protein samples.
- PTFE — hydrophobic and solvent-resistant. For aggressive organics and gas venting.
- Cellulose acetate / MCE — economical for aqueous filtration and microbiological analysis.
Pore size: what each one does
0.22 µm is the standard for sterilizing filtration — it retains bacteria and is the accepted cut-off for sterile media and buffers.
0.45 µm clarifies and removes particulates but does not sterilize. Common for HPLC sample prep and microbiological water testing.
Larger pore sizes serve as prefilters, extending the life of the sterilizing membrane when the sample carries heavy particulate load.
Protein binding matters more than you think
Filtering a dilute protein or a precious sample through a high-binding membrane can remove a measurable fraction of your analyte. For low-concentration proteins, growth factors and antibodies, use PES or PVDF and consider pre-rinsing the membrane. For routine buffer filtration, binding is rarely a concern.
Format and throughput
Syringe filters suit volumes up to about 100 mL. Bottle-top units handle 150 mL to 1 L and attach directly to standard media bottles. Vacuum manifolds and stainless holders serve higher-volume or repeated work.
If flow slows sharply mid-filtration the membrane has blinded — a prefilter or larger effective area will usually solve it.
Unsure which membrane suits your sample? Call +1 305 600 0444.