Bonding different chemical groups onto the surface of bare silica results in functionalized silicas which give higherselectivity towards specific molecules.
- Bare/Silica has a high polar surface, it is the most popular stationary phase, ideal for conventional applications (normal phase separations, non-polar target molecules, pharmaceuticals, natural products)
- C4; suited to molecules with large hydrophobic regions, peptides, proteins. Usually combined with a large pore size for big biomolecules (>1000Da)
- PHE/phenyl; moderately nonpolar for aromatic compounds, aflatoxins, caffeine, phenols.
- C8; highly hydrophobic pesticides, peptides, drugs
- C18; more apolar than C8 and in reversed phase chromatography higher retention than C8. Has a non-polar surface, ideal for pharmaceuticals, steroids, fatty acids, peptides, proteins, pesticides, PCB’s
- Amino/NH2has a medium polar surface, ideal for carbohydrates and nitrogen containing heterocycles and amines. Scavenger applications.
- Diolhas a lesspolar surface (than bare silica) and still many hydroxy-groups, ideal for lipids; Our best option for many SFC applications.
- Cyano/CN unique selectivity for polar analytes with widely different chemistry eg. Cyclosporine, carbohydrates
- Thiol/SH; Mainly used for scavenging
- SCX/SO4–:Ion Exchange for strong cation
- SAX/TMA; Ion exchange for weak anion
- NH2P; Ion exchange for scavenging