In the lab filtration process, a filter membrane is required. The material and type of filter membrane sometimes have a great influence on the sample, and different filter membranes need to be screened. The following briefly introduces the microporous filter membrane.
Microporous Filter Membranes Introduction:
Definition of microporous membrane filter:
- The membrane separation process is a method of separating mixtures using a thin film.
- As a selective pass-through phase between two phases, the membrane can allow one or more components in the two phases to pass through the membrane and retain other components, so as to realize the separation between different components and achieve separation, concentration, and purification.
- It mainly uses the fluid pressure difference as the driving force for the screening and separation process. Microfiltration, reverse osmosis, nanofiltration, and ultrafiltration are all pressure-driven membrane separation technologies.
Microporous filter membrane material：
- Microporous membranes filter material mainly include cellulose acetate membranes, mixed cellulose ester microporous membranes, nylon membranes
- And polytetrafluoroethylene membranes, polyvinylidene fluoride membranes (PVDF), polyethersulfone membranes, and PP filter membranes.
Microporous Filter Membranes Pore Sizes:
1. What are the differences in the pore size of the microporous membrane?
- Nominal microporous membrane pore size ratings are provided as a general indicator of membrane retention.
- It is understood that some particles larger than or equal to the nominal pore size will pass through the filter membrane and enter the filtrate.
- Some manufacturers may relate a nominal pore size rating to a percent filtration efficiency.
- Nominal pore size grades vary by manufacturer and therefore are not necessarily the same.
- Filters from manufacturers with similar nominal pore size ratings may not exhibit similar retention characteristics.
- Pore size ratings are often based on retention studies using standard microbial cultures or challenging suspended particles of known size.
- The pore size rating indicates the size of the small microorganisms or particles retained in these studies. Pore size ratings are almost always related to bubble point specifications used for quality control during membrane manufacturing. Most pore size grades, especially those based on microbial retention, are comparable between manufacturers.
- There is more uncertainty in pore size classes based on particle retention studies, especially for pore size classes < 0.2 µm, as there are no standard methods for these studies.
- And regardless of pore size, it is important to understand that conditions of use do affect particle retention. Even a filter with a nominal pore size can operate at the condition of allowing particles larger than the expected size to pass through.
2.Common pore sizes are 0.22μm, 0.45μm, 0.8μm, 1.0μm
a.0.22μm:
- It can remove the requirements of extremely fine particles in samples and mobile phases; meet the requirements of GMP or Pharmacopoeia, and the sterilization rate reaches 99.99%.
- It is suitable for the treatment of solvents and samples with high requirements such as ion-pair reagents and ultra-pure chromatography. Filtered water, mass spec solvent samples, etc. Applicable to packing chromatography systems smaller than 3μm, 3μm, or larger.
b.0.45μm:
- It can filter out most bacteria and microorganisms, is suitable for routine sample and mobile phase filtration, and can meet general chromatographic requirements
c.0.8μm, 1.0μm
- And can remove most insoluble particles, suitable for analysis and detection of relatively low sample content
