Chromatography involves separating a mixture by passing it through a separation medium that gradually traps solutes due to their size – in liquid chromatography (LC) a sample is dissolved in suitable solvent and passed through a separation medium as a liquid.

This could be done immediately ahead of analysis step, perhaps to see how much of a specific protein is within a sample, or it could be done to synthesise a highly purified material for later fabrication steps.

LC is commonly performed at high pressure (high-performance liquid chromatography (HPLC)), which his able to resolve to a higher degree, or in conjunction with a mass spectrometer (LC-MS) for immediate analysis.