About the Housing and Membrane of the Syringe Filter

Famous for easy and convenient uage, the syringe filter has been applied in many areas, such as biofuel analysis, HPLC sample preparation, environmental testing, routine control de calidad analysis, remove protein deposits, dissolution determination and food analysis and so on. Today, our main attention is on the two major compoments-housing and membranes.

Syringe filter housing

When the syringe filter is processing the chromatographic sample, it is necessary to avoid the introduction of other impurities during the filtration process. The appearance of this kind of impurities may be: the shell material or the filter membrane will shed particulates and be carried into the filtrate. Therefore, the material of the filter membrane and housing structure is very important.

The syringe filter structure is composed of two parts, housing and membrane. Syringe filter can be made of different materials. Usually housing is polypropylene pp or nylon polyamide. PP is a semi-crystalline thermoplastic. It has a wide range of applications in the industry and is one of the common polymer materials.

PA(nylon polyamide) has good comprehensive properties, including mechanical properties, heat resistance, abrasion resistance, chemical resistance and self-lubrication, and has low friction coefficient, certain flame retardancy, easy processing. There are many varieties of PA, including PA6, PA66, PA11, PA12, PA46, PA610, PA612, PAl010, etc., as well as new varieties of semi-aromatic nylon PA6T and special nylon developed in recent years.

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Commonly used membranes and their characteristics

From different standards, the syringe filter can be classified into different types, such as the liquid property classification: water phase filtration; organic phase filtration; filtration phase classification: gas phase filtration; liquid phase filtration; filter layer structure: single-layer membrane structure, multilayer membrane structure, capillary structure; and syringe filters with different menbranes, such as the PTFE, Nylon, PVDF and PP etc.

1. PTFE membrane

The PTFE membrane of PTFE syringe filter is made of PTFE, which is completely natural and permanently hydrophobic. With strong chemical compatibility, it can filter many solvents, like the corrosive chemicals and organic solvents.

2. Nylon membrane

Polyamide filter membrane (Polyamide, Nylon): used for alkaline solution and organic solvent filtration; nylon membrane has very good mechanical strength, strong adsorption, can withstand most organic solvents and most alkaline solutions, especially suitable for filtration of alkaline solutions. Due to the relatively high adsorption performance of nylon membranes, it is generally not recommended for the filtration of culture media or the filtration of biological samples.

3. PVDF membrane

PVDF membrane of PVDF membrane syringe filter has high hydrophobicity, so it needs to be soaked in an appropriate solution such as ethanol before use to achieve the purpose of activation and make it easier for the membrane to bind proteins. Compatible with many dyes, such as Ponceau-S red, Coomassie brilliantblue, Sypro ruby, Transillumination, Toluidine blue, CPTS, Colloidal gold, India ink and Amido black. Among them, dyes such as Ponceau and CPTS can be washed off after dyeing, and the membrane can be used for further analysis; while dyes such as Coomassie Brilliant Blue, India ink, and amide black are irreversible, and the membrane cannot be used after dyeing. For further analysis.

If you need to use fluorescence detection (such as using the LI-COR Odyssey system), you need to use a special low fluorescence background PVDF membrane.Positively charged PVDF can be used to remove endotoxins.

4. PP membrane

The thermal spray fiber flat membrane PP of PP syringe filter is divided into isotactic and atactic polypropylene due to the difference in the spatial arrangement of molecular chains. The PP membrane can tolerate most chemical solvents, in addition to strong oxidants at room temperature; it is used for impurities or particles in liquids or gases, not as a sterilization filtration, only for clarification filtration.

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