High Performance Liquid Chromatograph (HPLC Instrument)

High-performance liquid chromatography (HPLC) (also called high-pressure liquid chromatography) is a solution-phase technique for fractionation of complex samples. Unlike standard column chromatography, HPLC is an active process in which materials are pumped at high pressure through the separation column, which contains the so-called “stationary phase” of the separation in the form of densely packed, often chemically functionalized beads. Once introduced to the column, it is the sample’s differential affinity for the solvent (“mobile”) and stationary phases that enables separation to occur, generally with sharper resolution than standard liquid chromatography. High performance liquid chromatographs can be used for analytical or preparative applications depending on the HPLC pump and the column size. HPLC columns are available in a variety of formats, including reverse phase, ion exchange, and size exclusion, which separate based on polarity, charge, and size, respectively.