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Home » Blog » Can PTFE Syringe Filters Be Used for Air or Gas Sampling?



For laboratory analysis and research, selecting suitable filtration devices is of utmost importance. One such option that is often employed is the PTFE (polytetrafluoroethylene) syringe filter. Widely recognized for its excellent chemical resistance and efficient liquid filtration performance, the PTFE syringe filter is widely utilized; however, often raised is whether these filters could also be utilized for air or gas sampling applications. In this article, we will delve further into this question and investigate its suitability within these applications.


Understanding PTFE Syringe Filters


PTFE syringe filters feature hydrophobic membranes crafted of polytetrafluoroethylene, an inert synthetic fluoropolymer with unique properties. PTFE’s hydrophobic nature prevents wetting-out and makes this filter suitable for applications involving non-aqueous solutions with low surface tension as well as samples with non-zero surface tension. Various pore sizes (ranging from 0.45 um to 0.2 um), give precise control for specific requirements.


PTFE Syringe Filters Primarily intended for liquid filtration applications, PTFE syringe filters have become popular tools for clarifying and sterilizing solutions as well as removing particulates and bacteria, ensuring sample purity, as well as for clarifying and sterilizing solutions. Unfortunately due to their hydrophobic nature and inherent characteristics, they may not be the optimal choice when applied for air or gas filtration purposes.


Limitations of PTFE Syringe Filters for Air or Gas Sampling

PES Syringe Filter 0.45um: PES (polyethersulfone) syringe filters with a 0.45 um pore size are often recommended as effective filters to capture particulates or microbes found in air or gas samples, unlike their hydrophobic counterparts which may not do as much in capturing such pollutants.


0.25 um Filters: For accurate air and gas sampling analysis, more precise filtration may be necessary to achieve accurate analysis. While 0.45 um PTFE syringe filters can capture smaller particles and microorganisms more readily, 0.25 um filters provide even finer filtering that better capture smaller particles and microorganisms.


Hydrophilic PTFE Filters: By nature, PTFE filters are hydrophobic, meaning they repel water. While this characteristic makes liquid filtration easier, air or gas sampling with moisture present can present difficulties. Hydrophilic filters composed of cellulose acetate or mixed esters of cellulose provide better moisture retention as well as particle capture capabilities.


Whatman Uniflo: The Whatman Uniflo syringe filters are well known for their performance when applied to liquid filtration applications; however, they may not deliver optimal performance in air or gas sampling applications. Therefore, alternative filter solutions designed specifically to address air and gas filtration should be explored for best results.


Fiber syringe filters (also referred to as depth filters) are designed specifically for air and gas filtration, featuring densely packed fibers that capture particulates through various means such as impaction, interception, and diffusion. By contrast, PTFE syringe filters lack this intricate fiber structure necessary for effective air or gas filtration.


Puradisc 25 Syringe Filter: Though suitable for liquid filtration, the Puradisc 25 Syringe filter may not possess the characteristics required for air or gas sampling. Its hydrophobic PTFE membrane may fail to effectively capture airborne particles; hence the need for special air and gas filters specifically tailored for these uses.


Alternative Filters for Air and Gas Sampling


Air and gas sampling applications offer various filter options that offer exceptional performance and compatibility, such as these alternatives:


Filters with pore sizes of 0.2 um are widely employed for air and gas sampling applications, offering higher filtration accuracy that ensures the capture of smaller particles and microorganisms.


Pall Acrodisc 32mm Syringe Filters: Pall Acrodisc’s 32mm Syringe filters offer exceptional air and gas filtration performance and reliability, boasting hydrophilic membrane options to suit applications including air or gas sampling.


PTFE 0.22 um filters may not be the optimal choice for air or gas sampling, however, if they are necessary they would likely perform best with 0.22 um pores as opposed to larger sizes. Other materials and designs are recommended for improved filtration efficiency.


Syringe Filter 25mm: These filters with a diameter of 25mm are widely used for air and gas sampling applications, offering greater filtration area for faster sample throughput and more effective capture of airborne particles.




While PTFE syringe filters excel in liquid filtration applications, their hydrophobic nature and design restrictions make them unsuitable for air or gas sampling applications. To ensure accurate analysis of air or gas samples and to obtain precise analytical results more efficiently. Therefore, researchers should select alternative filters tailored specifically for such purposes as hydrophilic filters or ones with smaller pore sizes; doing so allows researchers to ensure the integrity of their samples while providing precise analytical results.


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