In HPLC sample preparation, syringe filters play a critical role. Particulates in samples can clog columns, shorten column life, destabilize detector signals, and compromise reproducibility. Pre-filtration removes these impurities, improving repeatability and baseline stability. Needle-style syringe filters provide a convenient single-use solution, ensuring samples are clean before injection, protecting both the column and the instrument, and enhancing analytical reliability

Key Characteristics of Different Filter Membrane Materials

PTFE (Polytetrafluoroethylene) Membranes

Chemical Compatibility: Exceptionally inert and resistant to nearly all organic solvents, acids, and bases, but hydrophobic—unsuitable for direct aqueous filtration. Ideal for high-polarity solvents (e.g., acetonitrile, DMSO), high-temperature, and corrosive environments. Releases virtually no extractables.
Flow Rate: Dense structure requires pre-wetting with organic solvent, resulting in relatively low flow rates.
Protein Binding: Hydrophobic surface yields minimal non-specific protein adsorption, making it ideal for trace-level analyses. Use Cases & Limitations: Best for harsh or highly polar organic samples (acid digests, reagent extracts). Not for water without pre-wetting; avoid membrane drying to prevent tears.

Nylon Membranes
Chemical Compatibility: Hydrophilic; compatible with water and most organic solvents. Common solvents like acetonitrile and DMSO are fully supported, while THF and high-concentration methanol are subject to caution. Stability declines in strong acids/bases. Flow Rate: Moderate—wets quickly and filters faster than PTFE, but generally slower than PVDF. Protein Binding: High non-specific adsorption—unsuitable for protein-rich samples requiring maximum recovery. Use Cases & Limitations: Versatile for routine organic solvent or buffered aqueous samples (e.g., acetonitrile, methanol). Rugged and autoclavable, but avoid protein or strong-acid/base samples.

PVDF (Polyvinylidene Fluoride) Membranes
Chemical Compatibility: Hydrophilic; stable with water, alcohols, and ketones under neutral to mildly acidic/basic conditions. Very low UV absorbance minimizes background interference. Flow Rate: High—wets easily, offering faster filtration than PTFE at the same pore size Protein Binding: Low—excellent for biological samples, proteins, and cell culture media.
Use Cases & Limitations: Ideal for protein/peptide or alcohol-based sample filtration. Sensitive to strong bases, which can degrade the membrane.

PC (Polycarbonate) Membranes
Chemical Compatibility: Smooth, robust surface compatible with many acids, salts, oils, and saturated hydrocarbons. Not resistant to methanol, ketones, ethers, or aromatics. Flow Rate: Very high—uniform pore distribution yields low backpressure and rapid flow. Protein Binding: Extremely low—glass-like surface prevents adsorption of proteins and large molecules.
Use Cases & Limitations: Suited for particle counting, microscopic particle analysis, and cell studies requiring absolute retention. Rarely used in routine organic HPLC due to solvent limitations.

Performance Comparison

Membrane	Chemical Compatibility	Flow Rate	Protein Binding	Applications & Limits
PTFE	Resistant to nearly all corrosive solvents; hydrophobic	Low	Very low	Harsh organic phases; not for aqueous without pre-wet
Nylon	Hydrophilic; good with ACN, DMSO; caution with THF, MeOH	Moderate	High	Routine organics/buffers; avoid proteins & strong acids
PVDF	Hydrophilic; stable with water, alcohols, ketones	High	Low	Biological/alcohol samples; avoid strong bases
PC	Smooth; good with acids, salts, oils; not for MeOH, ketones	Very high	Very low	Particle/microscopy; not routine organic HPLC

Selecting the Right Membrane for Your Sample

Harsh or High-Polarity Solvents + Trace Analysis: Use PTFE for its unrivaled chemical resistance and low extractables.

Biological Samples (Proteins) + Alcohol/Water: Use PVDF for minimal protein binding and broad solvent compatibility.
Routine Organic Solvents: Use Nylon for its general compatibility and durability—avoid protein or extreme pH.
Particle Counting/Microscopy: Use PC for precise pore size and negligible adsorption.

Note: Always consider sample chemistry, cost, and instrument requirements when making your final selection.

Aijiren offers a full range of high-quality syringe filters with PTFE, Nylon, PVDF, and PC membranes to meet all your HPLC organic-phase filtration needs. Contact us for samples or technical consultation, and let us help you choose the optimal filter solution.

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