In a very non-polar environment, hydrophilic molecules will tend to associate with each other. The hydrophilic molecules in the mobile phase will tend to adsorb to the solid support if the solid support on a chromatographic resin is also hydrophilic. Increasing the mobile phase polarity will subsequently decrease the adsorption and cause the elution of the molecules into the mobile phase. This mechanism is called Normal Phase Chromatography. It is a very powerful technique but often requires non-polar solvents. Due to safety and environmental concerns this mode is used mostly as an analytical technique and not for process applications.

The opposite of normal phase, or Reversed Phase Chromatography, results from the adsorption of hydrophobic molecules onto a hydrophobic solid support in a polar mobile phase. Decreasing the mobile phase polarity by using organic solvents reduces the hydrophobic interaction between the solute and the solid support resulting in de-sorption. The more hydrophobic the molecule the more avidly it will adsorb onto the solid support. This requires a higher concentration of organic solvent to promote de-sorption.  Reversed phase chromatography is another very powerful technique and it is effective for the separation of a very wide range of molecules. However, at process scale it is not typically used for proteins, due to the presence of the organic solvent which denatures many proteins and destroys their biological activity. Reversed phase chromatography is used very frequently as an analytical technique and there are many different stationary phases available for method optimization.