Editing Chromatography (section)

===Liquid chromatography===
[[File:Preparative HPLC.svg|thumb|upright=1.8|Preparative HPLC apparatus]]
Liquid chromatography (LC) is a separation technique in which the mobile phase is a liquid. It can be carried out either in a column or a plane. Present day liquid chromatography that generally utilizes very small packing particles and a relatively high pressure is referred to as [[high-performance liquid chromatography]].

In HPLC the sample is forced by a liquid at high pressure (the mobile phase) through a column that is packed with a stationary phase composed of irregularly or spherically shaped particles, a [[Monolithic HPLC column|porous monolithic layer]], or a porous membrane. Monoliths are "sponge-like chromatographic media"<ref name="González-González-2020"/> and are made up of an unending block of organic or inorganic parts. HPLC is historically divided into two different sub-classes based on the polarity of the mobile and stationary phases. Methods in which the stationary phase is more polar than the mobile phase (e.g., [[toluene]] as the mobile phase, silica as the stationary phase) are termed normal phase liquid chromatography (NPLC) and the opposite (e.g., water-methanol mixture as the mobile phase and C18 ({{chem name|[[octadecylsilyl]]}}) as the stationary phase) is termed reversed phase liquid chromatography (RPLC).