Cobetter Filter Membrane: A Trusted Guardian for Air Monitoring During the Autumn and Winter Pollution Season

From monitoring perspective, autumn and winter are the most challenging seasons of the year. One major factor is the increase in emissions associated with combustion-related activities. Incomplete combustion generates high levels of fine particles and precursor gases, which result in increased PM2.5 concentrations with more complicated chemical compositions.

Simultaneously, the adverse weather conditions further aggravate air pollution. Pollutants do not disperse easily due to temperature inversions, a reduced atmospheric boundary layer height, low wind speeds, and limited vertical air movement. Consequently, particulate matter remains suspended in the atmosphere for longer periods.

Autumn and winter are also the peak seasons of secondary aerosol formation. Under conditions of low temperature and high humidity, SO₂, NOx, and VOCs undergo chemical reactions to form secondary particulates, including sulfates, nitrates, and ammonium. These secondary components often account for a large proportion of PM2.5 mass during severe pollution episodes.

The Air Sampling Filter Membrane: The First Gatekeeper of Data Accuracy

The air sampling filter membrane is much more than a consumable in atmospheric monitoring. It is the primary medium for particulate matter collection and the foundation for all subsequent analytical results.

For gravimetric measurement, elemental analysis, ion chromatography, or carbon fraction analysis, the accuracy of the data depends entirely on what is collected on the membrane. Even the most sophisticated analytical tools can not correct errors introduced during sampling.

Consequently, atmospheric monitoring is becoming more and more concerned with the increasingly focuses on membrane properties like weight stability, background purity, chemical compatibility, and mechanical stability.

Understanding Monitoring Objectives Before Choosing a Filter Membrane

The key to choosing the right filter membrane is understanding the monitoring objectives. There are usually two broad types of atmospheric monitoring: ambient air monitoring and pollutant source monitoring, each with different technical requirements.

Ambient air monitoring should focus on levels of common air pollutants, such as particulate matter (TSP, PM10, PM2.5) and gaseous pollutants, such as SO2, NOx, CO, and O3. These values form the foundation of air quality control and regulatory conformance.

Then focus on the source analysis of PM2.5, clarifying the source composition of fine particulate matter provides a scientific basis for precise pollution control.

Source analysis of PM2.5

· Organic compounds (VOCs/SVOCs)

PAHs, dioxins, cholesterol, etc.

· Inorganic elements / heavy metals

· Water-soluble ions

Cl⁻, NO₂⁻, NO₃⁻, SO₃²⁻, SO₄²⁻, Na⁺, NH₄⁺, K⁺, Ca²⁺, Mg²⁺

· EC/OC (elemental carbon / organic carbon)

· Others

Fluorides, HCl, amide compounds, asbestos dust, radioactive particles

How to Choose Cobetter Air Monitoring Filter Membrane

The characteristics of the membrane should be selected according to the objectives.

Manual gravimetric sampling of ambient air TSP, PM10, PM2.5, and PM1

Polytetrafluoroethylene (PTFE) membranes are one of the most commonly used filter membrane materials in atmospheric monitoring. They are widely used for ambient air particulate matter (PM) sampling, especially for PM2.5.

Cobetter PM2.5 PTFE membrane filters are designed for atmospheric air sampling. They are made from high-purity PTFE with chemically resistant polypropylene support rings,which enhance handling stability and minimize the risk of deformation or damage during installation, transport, or analysis.

Another key advantage of PTFE membranes is their low elemental background.  This property makes them particularly suitable for analyzing inorganic elements like heavy metals and water-soluble ions.

The ring-supported PTFE membranes are manufactured in an ISO Class 7 cleanroom to minimize contamination and ensure consistent batch quality. Each membrane is sequentially printed with a unique serial number to facilitate traceability, data management, and quality auditing.

Features and Advantages:

• Precisely controlled pore size and DOP retention efficiency ensure accurate and complete sampling.
• Weight stability, combined with hydrophobic material, ensures sampling is not affected by ambient humidity.
• Extremely low metal ion background, suitable for particulate matter composition analysis.

PM2.5 source analysis and component analysis

Quartz microfiber filters and polytetrafluoroethylene (PTFE) filters, owing to their extremely low organic and inorganic backgrounds, are commonly used for EC/OC analysis in PM2.5 source analysis, as well as for the analysis of water-soluble ions and heavy metal elements.

Cobetter quartz fiber disc membranes are made from high-purity quartz fibers without binders. Their filtration efficiency at 0.3 µm exceeds 99.99% by DOP testing, making them suitable for high-reliability capturing of fine particulate matter.

High temperature resistance is one of the typical properties of quartz fiber membranes, they can withstand temperatures up to 900 °C. This characteristic makes them suitable for use in the sampling of high-temperature flue particulate and thermal-optical examination of carbonaceous substances.

Quartz fiber membranes are also highly resistant to gases and acids, and therefore can be used in chemically aggressive conditions. In addition, their low heavy metal content minimizes background interference, which is critical for the accurate determination of trace metal concentrations in airborne particulate matter.

Automated β-ray absorption sampling for ambient air PM10 and PM2.5 monitoring

XRF-dedicated PTFE roll filter membranes

Designed for XRF analysis with optimized composite membrane structures to support detection of trace elements at the lowest concentration levels.

Maximum Trace Element Detection Limits of XRF Composite Membranes

Cobetter operates a comprehensive portfolio of filter membrane production lines for atmospheric monitoring. Supported by a rigorous quality management system and extensive membrane material characterization and validation capabilities, Cobetter is committed to providing professional, reliable filtration products and environmental monitoring solutions.