Two of the most significant fractions of suspended particulate matter are the respirable fraction (< 2.5 μm) and the inhalable fraction (< 10 μm). Two important tests performed in air monitoring of particulate matter, PM 2.5 and PM 10, pertain to these two fractions. Whatman glass fiber filters from GE are recommended for gravimetric determination of airborne particulates, such as PM 10, stack sampling, and absorption methods of air pollution monitoring.
In the analysis of collected particulate matter, care should be given to the choice of the filter medium used. The filter medium should give little or no background level for the elements and/or compounds being analyzed and should cause minimal interference in the determination. Glass fiber filters and thimbles
Whatman glass microfiber filters (such as GF/A and EPM 2000) and quartz filters (such as QM-A) are particularly suitable for gravimetric determination of particulates due to the high retention efficiency of the media combined with rapid flow characteristics,low pressure drop, high loading capacity, and low affinity for moisture. PTFE membranes are often used for specific gravimetric analyses (e.g., PM 2.5 monitoring or vehicle emissions testing) according to the employed methodology.
Stack gases are often monitored at high temperatures for which glass microfiber or quartz filters, such as QM-A or thimbles, are appropriate. PTFE membranes
Whatman TE type and PM 2.5 are chemically resistant and possess low chemical background interference (e.g., metals), allowing the user to carry out sensitive determinations.
Whatman TE membranes are general purpose PTFE membrane filters that have multiple applications in environmental analysis.
PM 2.5 filters are used for the measurement of fine particulate matter in the atmosphere for the EPA PM 2.5 reference method (under the requirements of 40 CFR Part 50 Appendix L).
What are you testing for?
Particulate manual sampling: normal environment
Product
Glass fiber filters such as GF/A and EPM 2000
PTFE TE type
Glass fiber thimbles
PM 2.5 membranes
Characteristics and benefits
GF/A
Binder free
Glass fiber
Fine particle retention
High flow rate
Good loading capacity
EPM 2000
Binder free
Glass fiber
Used in high-volume PM-10 air sampling equipment
Detailed chemical analysis of trace pollutants
Glass fiber thimbles
Binder and binder free
Glass fiber
Used at temperatures up to 500°C
GF 10
Binder
Glass fiber
Extreme mechanical stability
Used up to 180°C
TE type PTFE membranes
Suitable for filtration of gases and liquids
Resistant to most acids, alkalis, and solvents such as sodium hydroxide and hexane
Laminated onto a nonwoven polypropylene support material
Increased durability for aggressive testing environments
Hydrophobic characteristics prevent passage of aqueous aerosols (e.g., during venting applications)
PM 2.5 membranes
Used for PM 2.5 ambient air monitoring
Conform to EPA PM 2.5 reference method under the requirements of 40 CFR Part 50 Appendix L
Do not contain glues or adhesives
Sequentially numbered for easy traceability of the filter
Chemically resistant polypropylene support ring, which eliminates curling and makes the filter robot-friendly
Retain a minimum of 99.7% of 0.3 μm size particulates
What are you testing for?
Particulate manual sampling: aggressive environment
(high temperature and acidic)
Product
Quartz fiber filter such as QM-A and QM-H
Characteristics and benefits
QM-A quartz fiber filters
High-purity quartz microfiber
Used for air sampling, particularly at high temperatures up to 500°C
QM-H quartz fiber filters
100% pure quartz
Can be used up to 900°C
Low heavy metal content
Quartz fiber thimbles
Made from high-purity quartz microfiber
Able to withstand high temperatures up to 800°C
Suitable for both solvent extraction and air sampling applications
What are you testing for?
Particulate automated sampling
Product
Glass microfiber reels
Characteristics and benefits
Binder
Glass fiber
Extreme mechanical stability
Used up to 180°C
What are you testing for?
Radioactivity
Product
Grade 72
SAS cards for static air sampling*
PAS cards for personal air sampling*
Glass fiber filters such as GF/A
Characteristics and benefits
Grade 72
Glass fiber/cellulose
Used to absorb radioactive iodine in air pollution monitoring and in nuclear installations
What are you testing for?
Metal chemical analysis
Product
Mixed cellulose ester membranes
Characteristics and benefits
Typically used in applications for the determination of metals in airborne particulates
* Please contact your representative for information on SAS and PAS cards
Chemical analysis
Heavy metals, organics, and inorganics
Air pollution monitoring from stacks, flues, and aerosols requires a filter that can withstand chemically harsh environments and high temperatures. High-purity quartz (SiO2) microfiber filters are favored for these reasons and their applicability for heavy metals analysis.
Quartz fiber filters and thimbles
GE offers two types of quartz filters—QM-A and QM-H. The low level of alkaline earth metals in these filters virtually eliminates artifact products of sulfates and nitrates (from SO2 and NO2, respectively). QM-H is a pure quartz fiber filter with low heavy metal content. Quartz thimbles are also available.
Mixed cellulose ester membranes
Mixed cellulose membranes from GE are designed to meet your environmental air monitoring requirements. These membranes are typically used in applications for the determination of metals in airborne particulates.
What are you testing for?
Heavy metals
Product
Quartz fiber filters such as QM-A and QM-H
EPM 2000 glass fiber filters
Characteristics and benefits
QM-A
High-purity quartz microfiber
Used for air sampling, particularly at high temperatures up to 500°C
QM-H
100% pure quartz
Can be used up to 900°C
Low heavy metal content
What are you testing for?
Other organic or inorganic chemicals
(such as ozone, volatile organic carbons, SO2, NO2, CO, Benzoate)
Product
Glass fiber filters such as GF/A
Quartz fiber filters such as QM-A and QM-H
Cellulose filters*
PTFE membranes
Characteristics and benefits
Quartz fiber thimbles
Made from high-purity quartz microfiber
Able to withstand high temperatures up to 800°C
Suitable for both solvent extraction and air sampling applications
* Please contact your representative for information on cellulose filters
Asbestos testing
Asbestos analysis is commonly undertaken by a number of microscopy techniques such as Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and Phase Contrast Microscopy (PCM).
These methods usually involve sampling and/or observation, both of which involve the use of membrane filters such as polycarbonate or mixed cellulose ester membranes.
Optical analysis for asbestos sampling
GE provides Whatman membranes for the main asbestos
sampling methods.
Transmission electron microscopy method
Two membrane materials are typically recommended for this method:
Mixed ester membrane (e.g., WME membrane)
Polycarbonate membrane (e.g., Whatman Cyclopore™ or Nuclepore™ membranes)
See the following tables for more information.
Phase-contrast microscopy method
One of the techniques used to optically determine the asbestos fiber count is the “hot block” method. Crucial to this method is the membrane filter that is used to collect fibers from a defined volume of air. During processing the membrane is made transparent with acetone vapor. Mixed cellulose ester membrane from GE is the recommendation for this application.
Scanning electron microscopy method
GE offers a range of polycarbonate membranes, Cyclopore and Nuclepore. Nuclepore is also available in a gold-coated format.
What are you testing for?
Asbestos
Product
WME mixed cellulose ester membrane
Characteristics and benefits
Typically used for Phase contrast microscopy (PCM) and Transmission electron microscopy (TEM)
Cellulose mixed ester membrane
Gridded, 0.8 μm pore size, 25 mm surface area with high loading capacity
High flow rates
Product
Nuclepore and Cyclopore
Characteristics and benefits
Manufactured with proprietary Whatman technology for controlled pore size distribution
Smooth, flat membrane; particles are retained on surface so are easily visible during optical analysis
Nuclepore available in two versions: gold coated or not gold coated
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