Reverse-phase HPLC

In reverse-phase HPLC, the stationary phase is non polar and the mobile phase is polar.

Reverse-phase HPLC is the most common HPLC method. When using reverse-phase, non-polar compounds (C) interact the most with the stationary phase and are retained more in the column and elute last, while the polar compounds (A) interact the most with the mobile phase and elute first.