Chromatography#Liquid chromatography

The liquid chromatograph in the default language also liquid chromatography (English: liquid chromatography; abbreviated LC) is a physical separation method as a special field of chromatography. Used as mobile phase is a liquid. It can be carried out either in a column or a plane. Modern methods are characterized here by a very small particle sizes and high Einstromdrücke.

We distinguish:

• Paper chromatography,
• Thin layer chromatography ( short DC) and
• Column chromatography Niederdruckflüssigkeitschromatographie and
• Performance liquid chromatography ( HPLC short )
• Ion-exchange chromatography (IC)
• Gel permeation chromatography (GPC)
• Supercritical fluid chromatography (SFC )

• Flow Field-Flow Fractionation Symmetric flow - field flow fractionation ( SF4 shortly )
• Asymmetric Flow Field-Flow Fractionation ( AF4 short )

A distinction is made open systems (eg thin layer chromatography, paper chromatography ), the stationary phase can be taken out and examined directly, and closed systems (eg, column chromatography, HPLC). In closed systems, the substances are isolated after elution with a solvent or displayed with a detector.

Whether this separation method can be used for separating a mixture of substances depends mainly upon whether all of the substances of the mixture can be dissolved in the mobile phase, and if there is a stationary phase having a sufficient selectivity between the substances. By elution or capillary action of the solvent, it is through the stationary phase in a sorting process according to the molecular characteristics. Through the trailing solvents substance zones can form, which can be collected from the bottom tube exit.

As stationary phases are often used (also known as silica ), and polymers, such as polystyrene -divinylbenzene copolymer ( PS / DVB), is used. Modified and non-modified silica gels In the field - flow fractionation, various separating fields ( flow fields, thermal fields, etc. ) is used as stationary phase.