What is the So-Called Chemically Bonded Phase?

The general chemically bonded phase uses silica gel as a carrier, which has a partitioning effect and a certain adsorption effect. The size of the adsorption depends on the bonding coverage.

The residual silanol groups on the surface of the support are removed by a chemical reaction, which is called end capping, capping, or covering. The bonded phase formed is called a tail-type bonded phase. The fully encapsulated bonded phase has no adsorption, but strong hydrophobicity is a disadvantage.

The silica-bonded phase is classified into Si-O-C and Si-O-C (siloxane) types according to the type of chemical bond in which the functional group is combined with the carrier. The Si-O-C type bonded phase is damaged due to hydrolysis and has been eliminated. At present, silicone-type bonded phases are often used, and they can be classified into non-polar, medium-polar, and polar types according to their polarities.

The octadecyl bonded phase is the most commonly used non-polar bonded phase. The octadecyl dichlorosilane reagent and the silanol group on the surface of the silica gel are subjected to a multi-step reaction to produce an ODS-bonded phase. Adsorption or partitioning depends on the ODS bonded phase coverage.