About the Commonly Used Pore Sizes and Materials of Filter Membranes

1. Pore size of membranes filter

Commonly used pore diameters are 0.22μm, 0.45μm, 0.8μm, 1.0μm

Pore sizeApplications
0.22μm0.22μm membrane filter can remove very fine particles in samples and mobile phases; it can meet the requirements of 99.99% sterilization stipulated by GMP or Pharmacopoeia. It is suitable for the processing of solvents and samples with high requirements, such as ion-pair reagents and ultra-pure reagents for chromatography. Filter samples of water, mass spectrometry solvents, etc. It is used in color chromatography systems with fillers smaller than 3μm, 3μm, or larger.
0.45μm0.45μm membrane filter can filter out most bacteria and microorganisms, suitable for routine samples and mobile phase filtration, and can meet general chromatographic requirements.
0.8-1.0μm0.8-1.0μm membrane filter can remove most insoluble particles, suitable for UV and other relatively low-demand analysis and detection of samples, higher efficiency than 0.45μm filter membrane, especially suitable for the use of insoluble excipients, suspensions, and adhesives, and the use of UV dissolution testing of oral solid preparations tested.
1-5μmFilter larger particles of impurities or pretreatment for difficult-to-handle turbid solutions. It can be filtered with a 1-5μm filter membrane and then filtered with the corresponding filter membrane.

hydrophobic ptfe membrane filter hydrophilic ptfe membrane filter 0.45 Disc Vacuum Microfiltration Membrane

2. Membrane Filter materials

Common filter membranes mainly include cellulose acetate membrane filter, mixed cellulose ester microporous membrane, nylon membrane filter, polytetrafluoroethylene membrane, polyvinylidene fluoride membrane (PVDF), polyethersulfone membrane, polypropylene membrane filter(PP). Please click here to know PVDF vs PTFE

Solvent propertiesMaterialApplications
Water systemCARelatively low protein adsorption, good hydrophilicity, strong chemical compatibility; pH 3-7; suitable for filtration of antibiotics, globulin, vaccine serum, and tissue culture medium, etc.; liquid sterilization, particle filtration, and other water-based samples.
PESHydrophilic membrane, large flux, both good throughput; low protein adsorption capacity, improving protein recovery application; good aging resistance, creep resistance, good chemical reagent resistance. It can be used for high-temperature liquid filtration, which is used in the filtration of biological and serum in the pharmaceutical industry, the terminal filtration of large infusion antibiotics, the terminal filtration of beverages and wine in the food industry, and the terminal filtration of ultrapure water.
PVDFThe hydrophilic system has excellent anti-aging and solvent resistance can be used for a long time at -40℃~150℃ and has low protein adsorption. PVDF filter is resistant to corrosion by various strong acids, alkalis, and solvents at room temperature. It can be used for general biological samples to be filtered twice and samples with high protein recovery rates. It is soluble in strong polar solvents such as DMAC and NMP.
MACHigh porosity, good interception effect; good hydrophilicity, large water flux; intolerant to organic solutions and strong acid and alkali solutions. It has the characteristics of good mechanical strength, strong thermal stability, and low adsorption, which is suitable for filtration of sterilization and particulate removal in laboratories and small production processes; sterilization and filtration of culture medium and culture liquid, etc.
Organic system (filtered water system requires pre-soaking (ethanol))Hydrophobic PTFEHydrophobic PTFE can filter almost all organic solvents, has high mechanical strength, can withstand high-temperature liquids, and filters air and particulate impurities. Unless pre-soaked, the filtered aqueous solution will be difficult to advance the filtered sample due to tension obstruction.
Water & organic system(organic resistance, filtered water system does not need to be pre-soaked)NylonThe nylon membrane filter is used for the filtration of alkaline solutions and organic solvents; It is an economical choice for laboratories, not only can filter water samples, but is also compatible with most organic solvents but it cannot be used for the filtration of acid solutions, halogenated hydrocarbons, aromatic hydrocarbons, and other solutions.
Hydrophilic PTFEUniversal membrane, high mechanical strength, which can withstand high-temperature liquids, can withstand high-temperature liquids, filter air, and particulate impurities. Compatible with all acid and alkali solutions, the best choice for harsh laboratories.