Can be used to predict bioavailability, for evaluation of product performance and manufacturing consistency. The BET method measures the‚ÄĮspecific surface area‚ÄĮwhich 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,‚ÄĮBET‚ÄĮ¬†

The BET instrument applied by Particle Analytical (Micromeritics Gemini 2375 and Gemini V) determines the specific surface area (m¬≤/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‚ÄĮof 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¬įC). 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 ‚Äď 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 ‚ÄĮunder vacuum or by nitrogen flow at elevated temperature Micromeritics Flowprep 061
Measuring range Micropores (0.35 ‚Äď 2.0 nm) 
Result Specific surface area in m¬≤/g or m¬≤/cm¬≥. 
Sample amount 1 ‚Äď 2 g of dry substance is typically required for analysis. 

Consult our Experts


Dr. Changyong Lu
QC Chemist

Dr. Anna Shevchenko
Principal Scientist


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