Normal phases for the SPE.

In Solid Phase Extraction (SPE) chromatography, there are several phases involved in the process. Here are the normal phases used in SPE chromatography:

1. Sample loading: In this phase, the sample to be purified or concentrated is introduced onto the SPE column or cartridge. The sample can be in liquid form or dissolved in a solvent.
2. Washing phase: After sample loading, a washing phase is used to remove unwanted components. This can be done by passing through a solvent that selectively washes away unwanted substances while retaining the target components on the SPE phase.
3. Elution: Elution is the phase in which the target components are extracted from the SPE phase. A suitable solvent is used to dissolve and flush the target components away from the SPE phase. This solvent can be selective to extract specific components or can be general to remove all desired components.
4. Concentration: After elution, the solvent can be removed to concentrate the target components. This can be done by evaporation, nitrogen expulsion or other suitable techniques to reduce the volume of the solvent and increase the concentration of the target components.

Each stage in the SPE chromatography process is importance to isolate the desired components and purify them from interfering substances. It is important to select the correct SPE column or SPE cartridge, as well as the appropriate solvents and conditions for each phase, depending on the nature of the sample and the desired analytical purpose.