Spin filters enable efficient concentration of biological and environmental samples ranging from microliters to hundreds of milliliters, streamlining preparation for analytical techniques like mass spectrometry, chromatography, or enzymatic assays.
Selection Criteria
Molecular Weight Cutoff (MWCO)
Membrane pore size, expressed as MWCO or nominal molecular weight limit (NMWL), should retain target analytes while allowing buffer/salt passage. Optimal selection retains 90-99% of proteins by choosing MWCO 1/3 to 1/2 the target molecular weight—for a 50 kDa antibody, select 10-15 kDa filters to maximize recovery while achieving 10-20x concentration.
Membrane Chemistry
- Regenerated Cellulose: Ultralow protein adsorption (<1 μg/cm²), minimal extractables; preferred for sensitive proteomics/peptides where >95% recovery is critical.
- Hydrophilic PVDF: Excellent flow rates (200-400 L/m²h·bar), chemical resistance to 50% organics; ideal for clarifying viscous protein solutions pre-HPLC.
- Hydrophilic PTFE: Exceptional mechanical strength (burst pressure >5 bar), steam sterilizable; used for aggressive aqueous buffers and tissue culture media clarification.
- Polyethersulfone (PES): Asymmetric structure yields highest flux (>500 L/m²h·bar); aqueous biologicals requiring rapid processing.
- Cellulose Acetate: Moderate hydrophobicity requires ethanol pre-wetting; suitable for non-critical applications despite 2-5% higher protein binding.
- Nylon: Broad pH stability (2-11), resists methanol/acetonitrile; higher protein adsorption (3-7 μg/cm²) limits to small molecule/sample prep.