Can be used to predict bioavailability, for evaluation of product performance and manufacturing consistency. The BET method measures the specific surface area which relates to the reactive surface of the sample, including the pore size distribution.
Specific Surface area and adsorption-desorption isotherm analysis will
- Give you additional value to correlate with particle size distribution when evaluation batch-to-batch variation of raw materials
- Help you to understand the surface properties of your particles
- Be the utmost critical quality attribute for the development of the dry powder inhalation products
- Be able to evaluate the porosity of your powder particles
- Be an essential parameter in the evaluation of surface changes due to crystallisation of amorphous spots during storage of micronised powders
- Becomes your first aid in the building of your QbD or DoE for micronisation and crystallisation process
For Material Experts:
Instrument specifications and measuring principle, BET
The BET instrument applied by Particle Analytical (Micromeritics Gemini 2375 and Gemini V) determines the specific surface area (m²/g) of pharmaceutical samples. The samples are dried with nitrogen purging or in a vacuum applying elevated temperatures. Unless otherwise instructed, we use P/P0 of 0,1, 0,2 and 0,3 as standard measurement points. The volume of gas adsorbed to the surface of the particles is measured at the boiling point of nitrogen (-196°C). The amount of adsorbed gas is correlated to the total surface area of the particles including pores in the surface. The calculation is based on the BET theory. Traditionally nitrogen is used as adsorbate gas. Gas adsorption also enables the determination of size and volume distribution of micropores (0.35 – 2.0 nm). The method used complies with Ph. Eu.2.9.26 Method II.
|Instrument||Micromeritics Gemini VII|
|USP/Ph. Eur.||Ph. Eu.2.9.26 Method II|
|Sample preparation||Samples dried under vacuum or by nitrogen flow at elevated temperature Micromeritics Flowprep 061|
|Measuring range||Micropores (0.35 – 2.0 nm)|
|Result||Specific surface area in m²/g or m²/cm³.|
|Sample amount||1 – 2 g of dry substance is typically required for analysis.|
Consult our Experts
Dr. Wenbo Wang
Dr. Anna Shevchenko
Bardestani R, Patience GS, Kaliaguine S (2019) Experimental methods in chemical engineering: specific surface area and pore size distribution measurements—BET, BJH, and DFT. Can J Chem Eng 97(11):2781-2791.
Brunauer S, Emmett PH, Teller E (1938) Adsorption of gases in multimolecular layers. J Am Chem Soc (60):309–319
Buckton G (1997) Characterisation of small changes in the physical properties of powders of significance for dry powder inhaler formulations. Adv Drug Deliv Rev 26(1):17-27.
Chu KR, Lee E, Jeong SH, Park ES (2012) Effect of particle size on the dissolution behaviours of poorly water-soluble drugs. Arch Pharm Res 35(7):1187-1195.
Darcy P, Buckton G (1998 ) Quantitative assessments of powder crystallinity: Estimates of heat and mass transfer to interpret isothermal microcalorimetry data. Therm acta 316(1):29-36.
Dilworth SE, Buckton G, Gaisford S, Ramos R (2004) Approaches to determine the enthalpy of crystallisation, and amorphous content, of lactose from isothermal calorimetric data. Int J Pharm 284(1-2):83-94.
Jiang Q, Zhao Y (2004) Effects of activation conditions on BET specific surface area of activated carbon nanotubes. Microporous and mesoporous mater 76(1-3):215-224.
Jójárt I, Sovány T, Pintye-Hódi K, Kása P (2012) Study of the behaviour of magnesium stearate with different specific surface areas on the surface of particles during mixing. J Adhes Sci Tech 26(24):2737-2744.
Malamatari M, Somavarapu S, Kachrimanis K, Bloxham M, Taylor KM, Buckton G (2016) Preparation of theophylline inhalable microcomposite particles by wet milling and spray drying: The influence of mannitol as a co-milling agent. Int J Parm 514(1):200-211
Mohan VB, Jayaraman K, Bhattacharyya D (2020) Brunauer–Emmett–Teller (BET) specific surface area analysis of different graphene materials: A comparison to their structural regularity and electrical properties. Solid State Commun (320):114004.
Odler I (2003) The BET-specific surface area of hydrated Portland cement and related materials. Cem Concr Res 33(12):2049-2056.
Sehaqui H, Zhou Q, Berglund LA (2011) High-porosity aerogels of high specific surface area prepared from nanofibrillated cellulose (NFC). Compos Sci Technol 71(13):1593-1599