As we know, one specification for C18 silica gel is carbon loading, why carbon loading will affect the HPLC column? For the same type of column, the higher of carbon, means the higher of carbon bonded, also means higher bearing capacity and loading capacity.

C8 column is a column used for reversed-phase chromatography. Typically, reversed-phase chromatography uses a hydrophobic stationary phase. However, solid support stationary phases or columns contain modified silica. Here, silica is a hydrophilic stationary phase. Additionally, it contains alkyl groups that are covalently bonded to silica to form a hydrophobic silica stationary phase. Meanwhile, the mobile phase of reversed-phase chromatography is aqueous phase. Therefore, the immobilization has a high affinity for non-polar compounds in the sample.

In particular, the C8 column contains an octyl carbon chain with eight carbons as alkyl groups, which are used to modify the silica column. Also, these carbon chains are relatively short. Therefore, this shortness reduces the hydrophobicity and density of the stationary phase. Therefore, non-polar compounds have shorter retention times and less separation in the C8 column.

C18 columns are the less expensive and common column type in reversed-phase chromatography. In addition, the type of alkyl group used in the modification is an octadecyl carbon chain in the C18 column. In contrast, it has a longer carbon chain. In addition, the density of the column in the C18 column is higher due to the higher number of carbons in the alkyl group. Therefore, the hydrophobicity of the C18 column is also high. Therefore, it allows longer retention times for non-polar compounds, resulting in better separations. Also, it reduces the smearing of separation curves.

In addition, C18 columns are better for separating more hydrophobic compounds, such as long-chain fatty acids. In contrast, C8 columns are more suitable for the separation of small organic compounds.

As a manufacturer of column chromatography silica gel, TLC plate, C18 silica and so on, our products are widely used in CBD oil purification, natural product purification, flash chromatography and analytical and preparative industrial chromatography.