A solid-phase extraction cartidge has C18 material. What is the reason behind that all the characteristic grape juice color get transferred to the packing material of the cartridge?
The reason why the grape juice color gets transferred to the packing material of a solid-phase extraction (SPE) cartridge with C18 material is due to the principle of adsorption. C18, which stands for octadecyl silica, is a common type of packing material used in SPE cartridges. It consists of hydrocarbon chains attached to a silica support.
In the case of grape juice, it contains various pigments and color compounds such as anthocyanins. These compounds are responsible for the characteristic color of the juice. When the grape juice passes through the C18 material, the hydrophobic nature of the C18 interacts with the hydrophobic components of the grape juice, especially the color compounds.
The C18 material has a higher affinity for these hydrophobic compounds compared to the other components of the grape juice. As a result, the color compounds selectively interact with and adhere to the C18 material, leaving behind the majority of non-colored components in the grape juice.
During the solid-phase extraction process, the grape juice is passed through the SPE cartridge, allowing the color compounds to be retained on the C18 packing material. Subsequently, the other components are washed away, leaving the color compounds trapped on the C18 material.
To specifically recover the color compounds from the C18 material, an elution solvent can be used. This solvent, typically a mixture of organic solvents, is capable of breaking the interaction between the C18 material and the color compounds, allowing them to be eluted and collected separately.
So, in summary, the hydrophobic C18 material in the SPE cartridge selectively interacts with the color compounds in grape juice, leading to their transfer and retention on the packing material.