Reversed-phase SPE cartridges use non-polar adsorbents (carbohydrates or polymers) on the stationary phase to separate organic solutes from the polar phase (water). The force between non-polar substances is van der Waals attraction, and the affinity of the agent to the solute mainly depends on its hydrophobicity.
1. Reversed Phase SPE Cartridges stationary phase: non-polar 2. The separation object of reversed-phase SPE cartridges: medium to non-polar substances 3. Reversed Phase SPE cartridges mobile phase: polar (aqueous solution) or medium polarity 4. Force between adsorbent and compound of reversed-phase SPE cartridges: van der Waals force or dispersion force 5. Commonly used reversed-phase SPE cartridges: octadecyl bonded silica gel (C18 SPE cartridges)