Consider Two Important Factors When Choosing Membrane Filters

Whether doing inorganic experiments, organic experiments, or physical and chemical experiments, filtration operations are essential. How to select membrane filters reasonably and quickly is a skill that every experimenter must master. With years of experience and strong technical support, HAWACH provides professional laboratory filtration and analysis products, including microfiltration products, microbial detection products, environmental monitoring products, filter membranes and roll membranes of various materials, and nucleic acid protein analysis transfer membranes, and so on.

Today the Hawach will discuss how to choose the right membrane filters for your research. It can be summarized into two factors, membrane material, and pore size.

1. Material of membrane filter (chemical compatibility)

When choosing a microporous membrane, the first thing to consider is chemical compatibility. HAWACH editor has chosen the most 10 frequently used filter membranes to discuss their features and applications.

1.1 PES membrane filter
·Features
Hydrophilicity, autoclave resistance, low protein adsorption and dissolution, high flow rate, and flux
·Application
1) Laboratory filtration of general reagents and samples
2) Filtration of ultra-pure water, food, beverages, etc.
3) Filtration of serum samples
hydrophilic ptfe membrane filter hydrophobic ptfe membrane filter how to choose fliter membrane
1.2 Cellulose acetate filter membrane (CA)
·Features
Hydrophilicity, low adsorption capacity, low non-specific binding capacity, thermal stability
·Application
1) Protein and enzyme filtration
2) One of the most widely used membranes in sample pretreatment filtration

1.3 MCE membrane filter
·Features
Hydrophilic, high flow rate, mixed with nitrocellulose and cellulose acetate
·Application
1) Analysis of microorganisms and particles
2) Sterility test

1.4 Nitrocellulose filter membrane (NC)
·Features
Hydrophilicity, weak acid resistance, high protein binding ability
·Application
1) Microbial detection and capture, etc.
2) Trace element analysis, etc.
3) Bioengineering, biochemical analysis, etc. in medical research and diagnosis

1.5 Polyvinylidene fluoride filter membrane (PVDF)
·Features
Good chemical stability, heat resistance, low protein adsorption, and high sensitivity
·Application
1) Gas and steam filtration, high-temperature liquid filtration, purification filtration of solvents and chemical raw materials
2) Purification of insoluble matter in oil
3) Separation and purification of chemical substances
hydrophobic membrane and hydrophilic ptfe membrane filter membrane nylon membrane filter
1.6 Polytetrafluoroethylene filter membrane (PTFE)
·Features
Hydrophobicity, wide chemical compatibility, good temperature resistance, strong acid and alkali resistance, chemically corrosive solvents and oxidants
·Application
1) In chemical, pharmaceutical, food, energy, and other fields, it can filter almost all organic solutions
2) Filtration of strong acids and alkalis
3) Filtration of high temperature liquid
4) Filtration of special chemical reagents
5) Clarification and filtration of gas

1.7 Nylon filter membrane (NY)
·Features
Hydrophilicity, good temperature resistance, high strength, good chemical stability, resistance to dilute acid and alkali, etc.
·Application
1) Sterilization and filtration of samples
2) Filtration of industrial water

1.8 Polypropylene filter membrane (PP)
·Features
Acid and alkali resistance, abrasion resistance, impact resistance, uniform micropore distribution, large filtration area, and good water permeability
·Application
Widely used in medicines, beverages, daily water, wastewater, air filtration, etc.

1.9 Polycarbonate nuclear track etching filter membrane (PCTE)
·Features
Hydrophilic, good chemical stability, thermal stability, absolute pore size, translucent film, low protein adsorption, low extraction
·Application
1) General filtration
2) Early cancer screening
3) Hematology testing
4) Filtration and sterilization of medicines, food, beverages, wine, etc.
Research on cell metabolism, cell migration, cell co-culture

1.10 Polyester nuclear track etching filter membrane (PETE)
·Features
Hydrophilic, with good chemical stability, thermal stability, absolute pore size, translucent membrane, low protein adsorption, low extraction, better solvent resistance than PCTE, and more suitable for filtering corrosive liquids.
·Application
1) General filtration
2) Hematology testing
3) Filtration and sterilization of medicines, food, beverages, wine, etc.
4) Filtration of corrosive samples

2. Pore size of the filter membrane

Based on our filtration purposes and experimental requirements, we should choose a membrane filter with a suitable pore size.
0.1μm: It is able to get rid of the mycoplasma in the sample.
0.2μm: It is able to remove 99.99% of bacteria and microorganisms, meet the sterilization requirements of GMP or Pharmacopoeia, and can also remove very fine particles in samples and mobile phases.
0.45μm: It can filter out most bacteria and microorganisms, and can meet the general chromatographic requirements for regular samples and equal flow filtration.
0.8μm and above: It can filter larger particles of impurities or the pretreatment of difficult and turbid samples. After pretreatment, select the corresponding filter membrane for filtration.

Hierarchical filtration

In order to better selectively filter particles according to particle size, multi-stage filtration can be performed with membranes of different pore sizes. This kind of filtration can be achieved by a filter holder, which can place multiple filter membranes in sequence. Large particles can be trapped on a membrane with a larger pore size through classification filtration so that it is easier to count and analyze through a microscope. A large number of small particles will be trapped on the next level of the microporous membrane. In the weight evaluation, the impurities on all grades of membranes will need to be considered.