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To choose silica gel for column chromatography, match the grade to the mixture you are separating, then match the pore size and the particle size to the resolution you need. Coarser, larger-pore grades flow fast and suit bulk or pre-cleanup work; finer, small-pore grades give sharper separations of similar compounds at the cost of higher back pressure and slower flow. Once you have those numbers, state the pore size, surface area and particle size you require on the order.
Our column chromatography silica gel is a white powder whose main component is SiO₂·nH₂O. It is insoluble in water, in inorganic acid and in common organic solvents, and it dissolves only in hydrofluoric acid and concentrated caustic soda solution. Because different substances are adsorbed and retained differently as the mobile phase passes, the gel separates and purifies mixtures — the basis of every column method built on it. Like all silica gel it also adsorbs moisture from the air, which is why it is supplied and stored sealed and dry.
We supply three industrial and reagent grades, differentiated by pore structure. This is the primary selection decision:
| Property | XCL-A | XCL-B | XCL-C |
|---|---|---|---|
| Pore diameter (Å) | 20–40 | 50–80 | 80–100 |
| Pore volume (ml/g) | 0.35–0.50 | 0.50–0.75 | 0.80–1.00 |
| Specific surface area (m²/g) | ≥ 600 | 400–600 | 300–400 |
| Chlorides (reagent grade) (%) | ≤ 0.02 | ≤ 0.02 | ≤ 0.02 |
| Iron (reagent grade) (%) | ≤ 0.02 | ≤ 0.02 | ≤ 0.02 |
The rule is the same one behind every silica grade: the pore structure should fit the molecules you are separating. A small-pore, high-surface-area gel gives more adsorption sites for small compounds, but a molecule too large for the pore is excluded from most of that surface. For bigger molecules — many natural products and macromolecules — a coarse pore grade with larger openings, or a dedicated macroporous chromatography silica gel, gives the molecules more accessible surface.
If your work is analytical rather than preparative, the flat-bed formats may suit you better — see our thin layer chromatography silica gel and TLC plates.
Particle size is specified to order and should be chosen against your column: smaller particles pack a tighter bed and resolve closer peaks but raise back pressure and need a finer frit; larger particles flow freely but flatten the separation. Because this is a process-specific choice, we set particle size on agreement with your requirement rather than quoting a single fixed figure. Tell us the column dimensions, flow rate and the resolution you need, and we will match the grade and particle size to it.
Give us the mixture you are separating, the column and flow rate, the target resolution, and the grade or pore size you are considering. We will recommend the XCL grade, the surface area and the particle size, and quote the quantity you need — prices on request.
Send your separation detail and column setup — we will match the grade, pore size and particle size and quote it.
