Determine whether the particle size be kept or filtered. All particles larger than their authorized pore size and larger than they will be retained by membranes. Examine whether the liquid or gas is to be filtered and whether the PTFE Syringe filter is chemically compatible. Think about each component's ability to withstand chemicals before it meets the filtrate. The color or surface pattern of the membrane may be significant depending on the procedure used. Hydrophilic or hydrophobic membranes, temperature, flow rate, throughput, and sterilization requirements should also be considered.
Types of Membrane Materials
The most common membrane used in analytical and laboratory filtration is the cellulose nitrate (CN) membrane. With aqueous solutions, the CN membrane provides the quickest flow rates and outstanding wetting characteristics.
Cellulose triacetate and cellulose diacetate are combined to form the cellulose acetate membrane, which produces a robust membrane in both lateral and longitudinal orientations. The membrane additionally exhibits low static charge, very low aqueous extractability, and strong solvent resistance to low molecular weight alcohols.
Compared to a pure nitrocellulose membrane, a mixed cellulose ester membrane offers a more uniform and smoother surface. This membrane is often used to measure or examine liquid or aerosolized particle concentrations.
Strong, naturally hydrophilic, and compatible with a wide range of aqueous solutions, including alcohols and solvents required in HPLC work, the nylon membrane is an excellent membrane material. A membrane made of polyether sulfone (PES) is hydrophilic and has poor protein binding. Low extractability is the result of not needing external wetting agents. In comparison to cellulose acetate membranes, the PES membrane typically offers a quick flow rate and superior chemical resistance. Strong, incredibly porous, and resistant to most chemically hostile solvents, potent acids, and potent bases is the PTFE membrane. The backing material imposes restrictions on chemical and thermal processes.
Molecular Weight Cut Off (MWCO)
Lowest molecular weight solute that the membrane can retain 90% of is known as the Molecular Weight Cut Off (MWCO). It is possible to utilize a membrane whose MWCO is the same as the solute's molecular weight for fast filtration in situations when some sample loss is acceptable. When material loss is a concern, the membrane's MWCO should be lower than the compound's molecular weight.
Pore Size (absolute)
The size at which, under given circumstances, a particle of a given size will be retained 100% effectively.
PrewetMembranes that are hydrophobic by nature must be prewetted before being used with aqueous filtrations. Use 5 mL of chromatography-grade methanol, acetone, or another appropriate fluid with low viscosity (>0.6 cp) for this, then rinse with 25 mL.
Conclusion
Before examination by techniques like HPLC, ion chromatography, gas chromatography, ICP, and dissolution tests, particle contaminants from liquid and gas samples are removed using syringe filters, and single-use membrane-based devices. The quality and consistency of analytical results are increased, and instrument downtime is decreased, with proper sample filtration. For quick and effective filtering, disposable syringe filters are frequently utilized. Applications should be used for selection. Nonsterile syringe filters are used for general filtration and sample purification, while sterile syringe filters are used to sterilize solutions or clarify sterile solutions. Syringe filters can be divided into two categories based on the membrane and filter housing. Both qualities need to work with the filtering program and solution.
Read More: Types of Filtration & Sterilization
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