Method of Selecting a Filter Membrane

As we all know, the filter membrane generally used in the lab is the microporous filter membrane, which is an essential product in the precise filtration process. It is necessary for the customers to carefully choose the correct filter membrane for an accurate filtration result in terms of its material and aperture.

Membrane Material

Depending on the different materials used, there are mainly five different types of filter membrane, including PTFE, PES, PVDF, Nylon, RC, and GF material. Basically, the PTFE filter membrane is available for all the solvents, such as acids and salts, due to its superior chemical compatibility. The PES membrane is suitable for the filtration of aqueous samples rather than the polar solution and strong acid solutions, like ketones, ester solutions.

The PVDF membrane could be specially applied in the purification of suspended particles in the air and sterilization in the fermentation industry with its high flow rate feature. The Nylon filter membrane could be used for most organic solvents, aqueous solutions, and strong acids as well, but not for dimethylformamide. The RC membrane is available for aqueous samples and organic solutions. The GF filter membrane is often used as a pre-filter before a more accurate filtration.

Membrane Aperture

There are three most common aperture sizes provided for different filtration purposes – pore size 0.22μm, 0.45μm, and 1.0μm. The 0.22μm membrane is suitable for the filtration of extremely fine particles in the samples. The 0.45μm membrane could filter most microorganisms, which can satisfy the filtration of regular samples and the general chromatographic requirements. The 1.0μm membrane is used for the filtration of most insoluble particles.