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The pharmacopoeia defines what a chromatography silica is — identity, purity and how it is tested. It does not fix one particle size or one surface area for you. In the British Pharmacopoeia, the particle size of a silica gel reagent is stated after the reagent name in the test where it is used. So when a buyer asks for "pharmacopoeia grade", the correct answer is to ask which monograph and which particle size applies to their method.
The BP carries silica gels for chromatography in Appendix I A, General Reagents — including grades distinguished by an R-number suffix.
| BP reagent | What the monograph states |
|---|---|
| Silica Gel for Chromatography R1, Nitrile | A very finely divided silica gel of porous, spherical particles with chemically bonded nitrile groups. The particle size is indicated after the name of the reagent in tests where it is used. Described as a fine, white or almost white, homogeneous powder, practically insoluble in water and in ethanol (96%). |
| Silica Gel G | Contains about 13% calcium sulfate hemihydrate; fine, white or almost white homogeneous powder, particle size about 15 µm. |
Read the R1 wording carefully — it is the single most useful sentence on this page. The pharmacopoeia deliberately leaves particle size open and points you back to the individual test. A supplier claiming "BP grade, 40–63 µm" is quoting a commercial convention, not a pharmacopoeia requirement.
Silica Gel G shows the pattern. The monograph fixes composition and purity, not pore structure:
That is a reagent identity specification: a defined composition, a defined assay, a defined pH. Nothing about pore diameter, surface area or particle-size distribution.
The USP does not define a "chromatography silica gel reagent" the same way. Instead, USP〈621〉Chromatography sets out how chromatography is run, and the USP column listing assigns packing identities by L-code — for example L1 (octadecyl silane, C18), L7 (C8) and L9 (nitrile groups). Normal-phase columns use an active adsorbent such as alumina, silica or carbon, packed into the column.
| What buyers ask for | What the pharmacopoeia actually guarantees |
|---|---|
| "Pharmacopoeia-grade silica gel" | Identity and purity per the monograph — not a particle size or a surface area |
| "60 Å, 40–63 µm" | A commercial grade convention defined on the supplier's own data sheet |
| "Certificate of analysis" | The document that ties the figures to a batch — see our batch documentation checklist |
So the correct specification for a purchase order has two layers: the pharmacopoeia monograph for identity and purity, plus the supplier's commercial specification for pore diameter, particle size, surface area, pH and loss on drying. One layer does not replace the other — and the second layer is where our column chromatography silica gel grades are quoted.
Written by the VEN Desiccant export team from the published text of the pharmacopoeia general reagents and the USP chromatography chapter, plus supplier technical data sheets for chromatography-grade silica gel. Drafting was AI-assisted; every figure and clause wording was checked against the sources named above and edited by our team before publication. We publish it so buyers stop treating "pharmacopoeia grade" as a particle-size specification. Confirm the current monograph and edition before writing it into a contract.
Last checked: 11 October 2026.
Send the method, the packing identity and the pore and particle size you need — we will match the grade and quote it.
