C18 Silica Gel (Octadecyl Phase)

C18 silica gel is the most widely used reversed phase material because it is both popular and versatile. It creates strong hydrophobic interactions, which allow it to separate a wide variety of organic compounds effectively.

In practice, C18 silica gel is often chosen for separating nonpolar to moderately polar compounds. For example, it works well with fatty acids, glycerides, polycyclic aromatics, phthalate esters, fat-soluble vitamins, steroids, prostaglandins, and PTH amino acids. Therefore, it has become a standard choice in many chromatography applications.

Bonded Phases (Functionalized)/C18 Silica Gel

Bonded Phases and Functionalized C18 Silica Gel

Sorbtech also offers C18 silica gel with a broad range of bonding chemistries. These options extend from high hydrophilicity, such as bimodal aqueous phases, to high hydrophobicity, such as trifunctional phases with advanced endcapping. As a result, you can select the exact C18 bonded phase that best matches your separation needs—whether you require higher retention for hydrophobic compounds or greater compatibility with aqueous mobile phases.

Type Functionality
C18 Aqueous Mixed Mode
C18 Aqueous II Mixed Mode
C18 MNE Monofunctional Non Endcapped
C18 MLE Monofunctional Low endcapped
C18 MHE Monofunctional High endcapped
C18 TNE Trifunctional Non Endcapped
C18 TLE Trifunctional Low Endcapped
C18 THE Trifunctional High Endcapped
silica gel bonded phase C18

Silica gel C18 is one of the most common stationary phases in high-performance liquid chromatography (HPLC). It comes from silica, a natural mineral, that is coated with a hydrophobic C18 hydrocarbon chain. Because of this design, the material separates compounds through hydrophobic interactions, making it both accurate and efficient.

In practice, labs use C18 silica gel for the analysis of pharmaceutical compounds, food additives, and environmental contaminants. In addition, it helps purify biological samples like proteins and peptides. Therefore, researchers and industry professionals often choose it for both routine work and advanced testing.

In reversed-phase HPLC, the stationary phase is hydrophobic while the mobile phase is water-based. In this setup, nonpolar compounds stick more strongly to the C18 chains. As a result, they move more slowly through the column and separate clearly from other compounds in the mixture.

Moreover, C18 silica gel works well beyond HPLC. It also supports solid-phase extraction (SPE) and gas chromatography (GC). For example, combining C18 with other phases improves separation of complex mixtures. Most importantly, this flexibility helps labs handle many sample types with one reliable material.