is a measure of the exposed surface of a solid sample on the molecular scale. The BET (Brunauer, Emmet, and Teller) theory is the most popular model used to determine the area; results according to the Langmuir model are also available. Samples are commonly prepared by heating while simultaneously evacuating or flowing gas over the sample to remove the liberated impurities. The prepared samples are then cooled with liquid nitrogen and analyzed by measuring the volume of gas (typically N2
or Kr) adsorbed at specific pressures. Krypton gas is used when the measured surface is expected to be less than 2 m2
/g, which typically includes pharmaceutical samples and natural organic materials. We use several types of instruments for measuring surface area, the instrument selected depends upon the extent of the surface or the gas required to achieve the best results.
Instruments in our lab for Surface Area:
- N2 surface area
- Kr surface area
- Single point BET surface area tests using flowing gas technique
- BET Surface Area