Types of SPE Separation

SPE is typically used for the preparation of liquid samples and for the extraction of difficult or non-volatile samples, as well as for pre-extracting solid samples into solution.
How is the compound adsorbed and retained on the SPE filler?

Reverse phase solid phase extraction (polar liquid phase, non-polar solid phase)
Hydrophobic interaction
1. Non-polar-nonpolar interaction
2. Van der Waals force or dispersion force

Normal phase solid phase extraction (non-polar liquid phase, polar solid phase)
Hydrophilic interaction
1. Polarity – Polar interaction
2. Hydrogen bond
3.π – π interaction
4. Dipole-dipole interaction
5. Dipole-induced dipole interaction

Ion exchange extraction
1. Charged compounds are electrostatically attracted to the surface of the charged adsorbent
2. Adsorption (the role of compounds and adsorbent materials)
3. Hydrophobic interactions or hydrophilic interactions, depending on the solid phase material you choose.