We use cookies to measure traffic and to show relevant advertising. Nothing is stored or sent until you choose, and you can change your choice at any time.
ISO 9277 specifies how to determine the overall specific external and internal surface area of disperse or porous solids by gas adsorption — the method universally referred to as BET. If a supplier's certificate quotes a surface area without naming gas adsorption and ISO 9277, you do not know what was measured.
ISO 9277:2010 specifies the determination of the overall specific external and internal surface area of disperse solids (for example nano-powders) and porous solids by gas adsorption. A later edition, DS/ISO 9277:2022, is in circulation — so a certificate should also state which edition was used.
The keyword is "overall": BET returns the combined external and internal surface, which is exactly what you want for a porous adsorbent, where most of the available surface sits inside the pores rather than on the outside of the grain.
| Material | Typical BET surface area |
|---|---|
| Silica gel, 60 Å, column chromatography grade | ≈ 500 m²/g (typical supplier range 470–530 m²/g) |
| Silica gel, 100 Å wide-pore | ≈ 300 m²/g |
| Activated alumina (comparison) | ≈ 200 m²/g |
These are typical supplier values, not guaranteed limits, and they move a little from batch to batch. The grade is defined by the nominal pore diameter; the actual figure belongs on the certificate of analysis.
| Field | Why it matters |
|---|---|
| Surface area (BET, ISO 9277) with edition | capacity benchmark |
| Pore diameter and pore volume | which molecules can enter the pore |
| Particle-size distribution | resolution against flow and back pressure |
| pH | surface chemistry and method reproducibility |
| Loss on drying / water content | directly sets the remaining adsorption activity |
| Metal content / extractables | interference in chromatographic separations |
| Batch number and production date | traceability |
The full document set a buyer will ask for is listed in our batch documentation checklist.
BET is a gas-adsorption measurement, so the lab needs enough surface to measure reliably. Testing services commonly state minimum sample requirements in terms of total surface area rather than mass — for example a minimum around 10 m² of total surface, which for a low-surface powder means several grams but for a ≈500 m²/g silica means far less material. That is lab practice rather than a clause of the standard, but it explains the request when it arrives.
Written by the VEN Desiccant export team from the ISO 9277 standard summary and published supplier specifications for chromatography-grade silica gel and alumina. Drafting was AI-assisted; the standard's scope wording, the edition dates and the typical values were checked against the sources named above and edited by our team before publication. We publish it to help buyers read a certificate critically. The minimum-sample figures reflect published laboratory practice, not a clause of ISO 9277 — confirm against the edition you are working to.
Last checked: 11 October 2026.
Ask for the grade you are specifying and we will return the surface area, pore and particle data with the method named.
