autoflow BET instrument
scientist doing BET testing
BET analysis instruments

BET Specific Surface Area

BET Specific Surface Area is the most widely recognized technique for determining the surface area of solids and powders.  Samples are first prepared by drying, with a flow of inert gas or vacuum atmosphere, to clear the surface of any contaminants. The sample is introduced to cryogenic temperature to allow a probe gas to physically adsorb to the surface of the sample.  The volume of probe gas adsorbed is measured to determine the quantity of gas required to cover the surface of the sample.  The Brunauer, Emmett and Teller (BET) theory is then applied to the adsorption data to generate a specific surface area, reported in units of area per mass of sample (m2/g).

BET Specific Surface Area is recognized by numerous standards and guidance agencies, including the ISO, ASTM, USP and EP.  The ability to measure a broad range of surfaces from non-porous solids to highly porous powders has proven the technique valuable across multiple industries including pharmaceutical, environmental, automotive, chemical, cosmetic, geological, and food industries.

Many physical characteristics can influence the surface area of a sample, including particle size, pore size, pore volume and surface roughness. For this reason, BET Specific Surface Area has been used by our clients to help identify process manufacturing issues, differences between supplied vendor products, research and development troubleshooting as well as routine quality control and batch testing purposes across a wide range of products.

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Advantages

  • Multiple instrument model offerings to ensure the proper measurement for your sample
  • Nitrogen and Argon adsorptive gases are available for varying material types and sample properties
  • Can provide comparative data between samples when other physical characterization techniques are not feasible or practical

Considerations

  • 1-point BET is appropriate for a quick analysis for quality control, with an established linear BET. Recommend at least 3-point BET analysis
  • BET testing alone does not provide pore measurements; these would be determined with a gas physisorption isotherm analysis
  • Appropriate for dry material only

Sample Requirements

The sample must be a dry solid to be analyzed. Ideal sample amount is 2 to 5 grams. If sample availability is limited, please contact PTL.  Smaller sample quantities may be accommodated depending on sample properties.

For additional questions on your sample needs, please contact us to share specifics about your sample and options for suitable sample quantities.

Detection Range

PTL’s Surface Area department can measure from 0.01 m2/g to > 1000 m2/g depending on the adsorbate gas utilized and instrument manufacturer.

Data Reported

The BET (Brunauer, Emmett and Teller) theory is commonly used to evaluate the gas adsorption data and generate a specific surface area result expressed in units of area per mass of sample (m2/g).

Specific surface area can also be expressed in units of area per volume of sample (m2/cm3). This value is termed volume-specific surface area (VSSA) and is obtained by multiplying the BET specific surface area with the true density of the material. VSSA can be provided upon request if the true density of the material is measured or supplied with the sample.

Instrumentation

Particle Technology Labs has some of the top players in the industry, such as Micromeritics and Anton Paar/Quantatec.

Anton Paar/Quantatec AutoFlow BET+

Micromeritics 3Flex

Micromeritics Tristar II 3020

Anton Paar NOVA 800

Anton Paar/Quantatec Autosorb iQ-C-XR

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