High performance liquid chromatography (HPLC) is a very powerful technique that can be used to identify, quantify or purify components of a mixture.

As shown below, HPLC uses a column filled with fine beads that form the stationary phase and a solvent (or mobile phase) that moves over the stationary phase in the column due to the pressure generated by the pump.

HPLC output is recorded as a chromatogram. Compounds that interact the least with the stationary phase, move faster and have a shorter retention time. Compounds that interact the most with the stationary phase, move slower and have a longer retention time.

Diagram demonstrating the flow through an HPLC instrument. On the left, a flask with solvent represents the mobile phase. A black arrow flows from the solvent through a pump. A jar containing sample compounds A B and C is injected after the pump, and joins the black arrow that flows into a column containing stationary phase. The stationary phase column shows one blue dot moving slower than 3 green dots and 4 red dots moving fastest through the stationary phase. A black arrow flows out of the stationary phase into a detector represented by a green square with a brown rectangle in it. A dotted line connects the detector to a computer data station displaying a chromatogram with red peak first, green peak second and blue peak last. Finally a black arrow from the detector flows into a waster beaker.

Figure 1. Components of an HPLC instrument