3 Aspects You Should Know About Microporous Filter Membranes

Microporous membrane is a kind of polymer membrane material, with many uniform micropores, the pore diameter ranges from 0.025 to 14μm, and its filtration mechanism is mainly physical sieving. To be more exact, it is a polynuclear membrane composed of tens of thousands of micropores. The advantages are high porosity, fast filtering speed, small adsorption, no retention of liquid medicine, no influence on the content of medicine, simple equipment, convenient removal, etc. HAWACH is specialized in manufacturing microporous membranes, such as Nylon, PTFE, PTFE-L, MCE, PES, CA, PVDF, and GF, and their shape can be round or in a roll.
Today, HAWACH will discuss the 3 aspects you should know about microporous filter membranes.

1)Size of microporous filter membranes

filter volume(cm2)0.10.653.94.6
residual volume(ml)≤11-1010-10010-200
maximum operating pressure(psi)<10<25<100<125

2)Aperture of microporous filter membranes

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

Pore sizeApplication range
0.22μmIt can remove the requirements of extremely fine particles in the sample and mobile phase; it can meet the requirements of 99.99% sterilization specified by GMP or Pharmacopoeia. It is suitable for the processing of high-demanding solvents and samples, such as ion-pairing reagents for chromatography and ultrapure. Samples of water, mass spectrometry solvents, etc. are filtered.
0.45μmIt can filter out most bacterial microorganisms, suitable for routine sample and mobile phase filtration, and can meet general chromatographic requirements
0.8-1.0μmIt can remove most insoluble particles, is suitable for UV and other analysis and detection of samples with relatively low requirements, and the efficiency is higher than that of 0.45μm filter membrane, especially suitable for more insoluble excipients, large amounts of suspending agents, and binders, and use Dissolution testing of oral solid dosage forms by UV detection.
1-5μmIt can filter larger particles of impurities or for pretreatment of difficult-to-handle turbid solutions.

3)Different types of microporous filter membranes

Microporous filter membranes mainly include cellulose acetate membrane, mixed cellulose ester microporous membrane, nylon membrane, polytetrafluoroethylene membrane, and polyvinylidene fluoride membrane (PVDF), polyethersulfone membrane, poly Propylene filter membrane (PP filter membrane). The following describes the main applications for each type.

Solvent PropertiesMembrane materialScope of application
Water systemCellulose acetate(CA)It has low protein adsorption, good hydrophilicity, and strong chemical compatibility; pH 3-7; suitable for filtration of antibiotics, globulin, vaccine serum, and tissue culture medium; liquid sterilization, particle filtration, and other water-based samples.
Polyethersulfone(PES)This is a hydrophilic membrane, with large flux and good throughput; low protein adsorption, improving protein recovery; good aging resistance, good creep resistance, and good chemical resistance, and can be used for high-temperature liquid filtration. It is suitable for the filtration of biology and serum in the pharmaceutical industry, the terminal filtration of antibiotics in large infusions, the food industry like the terminal filtration of beverages and wine, and also it’s applied in ultrapure water terminal filtration.
polyvinylidene fluoride (PVDF)It can resist the corrosion of various strong acids and alkalis, that is, solvents at room temperature. It can be used for two passes of general biological samples, as well as sample filtration with high protein recovery.
mixed cellulose (MCE)It features a good retention effect, hydrophilicity, mechanical strength with high porosity, and large water flux. It is suitable for sterilization and particle removal filtration in laboratories and small production processes; sterilization filtration of culture medium and culture medium, etc.
Organic system (filtered water system needs to be soaked in advance (ethanol))Hydrophobic PTFEIt can filter almost all organic solvents, high mechanical strength, high-temperature resistance liquid, filter air, and particulate impurities. Unless pre-impregnated, the filtered aqueous solution will have difficulty advancing the filtered sample due to tension hindrance.
Water-based organic general purpose (organic-resistant, filtered water-based systems do not require pre-soaking)NylonIt can be used for filtration of alkaline solutions and organic solvents; nylon membrane has very good mechanical strength, and strong adsorption, can withstand most organic solvents and most alkaline solutions and is especially suitable for filtration of alkaline solutions. Nylon membranes are more economical and practical than PTFE membranes when used for organic solvent filtration, such as HPLC mobile phase particle removal. Due to the relatively high adsorption performance of nylon membranes, it is generally not recommended for medium filtration or filtration of biological samples such as protein liquids, in order to avoid sample loss due to adsorption. In this case, it is usually more suitable to use a low-adsorption cellulose acetate membrane (CA). An economical choice for the laboratory, it can not only filter aqueous samples but also is compatible with most organic solvents. Pls, note the acid solutions are excluded.
Hydrophilic PTFEIt is a universal membrane with high mechanical strength, can withstand high-temperature liquids, can withstand high-temperature liquids, filter air, and particulate impurities.