Silica Gel Adsorbents
By: Shyam Verma, Market Segment Manager, Reagents & Chemicals shyam.verma@sial.comAnalytix, Volume 9 Article 3
Broadest selection at economical price
Silica gels are used as an adsorbent in numerous applications, including chromatographic separations and removal of impurities through adsorption. In chromatography or column chromatography, the stationary phase is most often composed of silica gel, and due to its polarity, non-polar components elute before the polar components (normal phase chromatography). On the other hand, silica gels with C18 type hydrophobic groups attached to its surface allow elution of polar components first and are used in reversed-phase chromatography. Silica is also used in thin-layer chromatography. Silica gel exhibits strong desiccant properties and, therefore, is also frequently used in applications for control of relative humidity.
Sigma-Aldrich offers a broad selection of silica gels
- With a broad particle size range
- Products from leading manufacturers (Davisil® and Merck)
- Modified/bonded silica gels
- Generic silica gel for FLASH chromatography (for rapid preparative separations)
- Specialised silica gels for scavenging
These materials are useful for all types of low and medium pressures, and can be applied to cleanup and purification of a wide range of synthetic and natural compounds. Sigma-Aldrich offers a wide selection of silica gels and silicic acid for non-chromatographic purposes.
A wide-particle size range of silica gels is offered to meet your application requirements. Our products are especially economical for high-volume usage applications, while exhibiting quality comparable to products offered by other leading manufacturers. Table 1 presents our selected products grouped into two particle size ranges, along with comparable Merck and Davisil brands.
Table 1. Silica gels from Sigma-Aldrich and comparable Davisil and Merck products
| Grade | Brand | Particle Size | Pore Volume (cm3/g) | Pore Size (Å) | Surface Area (m2/g) | Size | Cat. No. |
| Particle size range: 35 –75 µm | |||||||
| - | Sigma-Aldrich | 200 – 425 mesh 35 –75 µm |
0.75 | 60 | 470-530 | 500 g 2.5 kg 5 kg 25 kg |
645524-500G 645524-2.5KG 645524-5KG 645524-25KG |
| - | Sigma-Aldrich | 200 – 425 mesh 35 –75 µm |
0.75 | 60 | 500 | 500 g 1 kg 10 kg |
288594-500G 288594-1KG 288594-10KG |
| - | Sigma-Aldrich | 200 – 425 mesh 35 –75 µm |
0.8 | 60 | 500 | 250 g 1 kg 25 kg |
60738-250G 60738-1KG 60738-25KG |
| - | Sigma-Aldrich | 200 – 425 mesh 35 –75 µm |
0.8 | 60 | 530 | 500 g 2.5 kg |
60737-500G 60737-2.5KG |
| 633 | Davisil | 200 – 425 mesh 35 –75 µm |
0.75 | 60 | 480 | 100 g 1 kg |
236772-100G 236772-1KG |
| 9385 | Merck | 230 – 400 mesh 40 – 63 µm |
~0.8 | 60 | 550 | 100 g 1 kg 5 kg 25 kg |
227196-100G 227196-1KG 227196-5KG 227196-25KG |
| - | Sigma-Aldrich | 70 –230 mesh 63 –200 µm |
0.75 | 60 | ~500 | 250 g 1 kg 5 kg |
288624-250G 288624-1KG 288624-5KG |
| High purity | Sigma-Aldrich | 70 –230 mesh 63 –200 µm |
0.8 | 60 | 500 | 500 g | 60740-500G |
| - | Sigma-Aldrich | 70 –230 mesh 63 –200 µm |
0.8 | 60 | 500 | 1 kg 6x1 kg 25 kg |
60741-1KG 60741-6x1KG 60741-25KG |
| Fluorescence indicator | Sigma-Aldrich | 70 –230 mesh 63 –200 µm |
0.8 | 60 | 500 | 1 kg | 60743-1KG |
| 634 | Davisil | 100 –200 mesh 75 –150 µm |
0.75 | 60 | 480 | 100 g 1 kg |
236780-100G 236780-1KG |
| 7734 | Merck | 70 –230 mesh 63 –200 µm |
~0.8 | 60 | 550 | 100 g 1 kg 5 kg 25 kg |
391484-100G 391484-1KG 391484-5KG 391484-25KG |
| 7754 | Merck | 70 –230 mesh 63 –200 µm |
~0.8 | 60 | ~500 | 25 g 100 g 500 g |
403598-25G 403598-100G 403598-500G |
Table 2 lists the Davisil silica gels of different particle sizes that Sigma-Aldrich® offers to meet your performance criteria. These products are commonly used in preparative column chromatography applications. The silica gels are already processed to minimise or eliminate impurities, such as minor metallic oxides that can modify the surface and unpredictably alter the adsorption process. Davisil silica grade 12 is recommended for ASTM method D-2007 for rubber extender processing oils. Grade 923 meets ASTM-1319-70 specifications for hydrocarbon analysis. Its low metal oxide content minimises olefin polymerisation.
Table 2. Other offered Davisil and Merck silica gels
| Grade | Brand | Particle Size | Pore Volume (cm3/g) | Pore Size (Å) | Surface Area (m2/g) | Size | Cat. No. |
| Grade 12 | Davisil | 28 –200 mesh 75 – 650 μm | 0.43 | 22 | 800 | 250 g 1kg 5 kg |
214396-250G 214396-1KG 214396-5KG |
| Grade 62 | Davisil | 60 –200 mesh 75 –250 μm | 1.15 | 150 | 300 | 100 g 500 g 2.5 kg |
243981-100g 243981-500g 243981-2.5KG |
| Grade 635 | Davisil | 60 –100 mesh 150 – 250 μm | 0.75 | 60 | 480 | 1 kg |
236799-1KG |
| Grade 636 | Davisil | 250 – 500 mesh 35 – 60 μm | 0.75 | 60 | 480 | 100 g 1 kg 25 kg |
236802-100G 236802-1KG 236802-25KG |
| Grade 643 | Davisil | 200 – 425 mesh 35 –70 μm | 1.15 | 150 | 300 | 100 g 1 kg |
236810-100G 236810-1KG |
| Grade 644 | Davisil | 100 –200 mesh 75 –150 μm | 1.15 | 150 | 300 | 100 g 1 kg |
236829-100G 236829-1KG |
| Grade 645 | Davisil | 60 –100 mesh 150 – 250 μm | 150 | 300 | 550 | 100 g 1 kg |
236837-100G 236837-1KG |
| Particle size range: 63 – 200 μm | |||||||
| Grade 646 | Davisil | 250 – 500 mesh 35 – 60 μm | 1.15 | 150 | 300 | 100 g 1 kg |
236845-100G 236845-1KG |
| Grade 923 | Davisil | 100 –200 mesh 75 –150 μm |
0.4 | 30 | 75 | 50 g 250g 1Kg |
214477-50G 214477-250G 214477-1KG |
| Grade 653XWP | Davisil | 230 -400 mesh 35 –75 μm |
1.1-1.2 | 300 | 150-170 | 100 g | 13660-100G |
| Grade 663XWP | Davisil | 230 – 400 mesh 35 –70 μm | 1.1-1.2 | 500 | 78-85 | 100 g | 13662-100G |
| Grade 10180 | Merck | 63 –200 μm | ~ 0.68 | 40 Å | 750 | 100 g 1 kg 5 kg |
403563-100G 403563-1KG 403563-5KG |
| Grade 10181 | Merck | 200 – 500 μm | ~ 0.68 | 40 Å | 675 | 100 g 500 g 2 kg 100 g 500 g |
242179-100G 242179-500G 242179-2KG 403598-100G 403598-500KG |
| Grade 10184 | Merck | 70 –230 mesh | - | 100Å | 300 | 100 g 1 Kg 5 Kg |
403601-100G 403601-1KG 403601-5KG |
| Grade 15111 | Merck | 15 – 40 μm | ~ 0.8 | 60 Å | 550 | 100 g | S9258-100G |
The Merck silica gels that we offer (see Table 2) are widely used for column chromatography. These adsorbents are pure (iron <0.02 % and chlorine <0.02 %), and demonstrate consistent particle size and defined pore structure. The most popular products are listed by Grade (EM catalogue number). For the proper Merck designation, simply insert Silica Gel or Kieselgel before the pore size – for example, Silica Gel 40 or Kieselgel 40.
Grade 7754 silica gel is an extra-pure material (each Cd, Cu, Pd, PO3 and Zn is<0.0005 %, Cl<0.008 %, Fe<0.002 %, NO3<0.004 %, and SO2<0.003 %). Grade 9385 silica gel for Flash is widely used for purification of organic synthesis products by gas-pressurised liquid chromatography.
Sigma-Aldrich also offers Flash columns and a full line of other supplies needed for Flash chromatography.
