What is Countercurrent Chromatography

Countercurrent chromatography can be broadly characterized as a form of liquid-liquid chromatography (LLC) in which two mutually saturated immiscible liquids are employed. One phase is retained in the chromatograph as a long continuous or segmented stationary bed without the use of an absorptive matrix; the second phase passes through

Louwerse DJ, Boelens HFM and Smit HC (1992) Single-sequence correlation chromatography. A novel technique to decrease detection limits. Analytica Chimica Acta 156: 349-359. Louwerse DJ, Smit HC and Kaljurand M (1997) Monitoring time-varying concentrations in sample streams by multiple input chromatography. Analytica Chimica Acta 346: 285-297. Mars C and Smit HC (1990) Sample introduction in correlation chromatography. Application, properties and working conditions for a novel injection system. Analytica Chimica Acta 220: 193-208. Smit HC, Mars C and Kraak JC (1986) Simultaneous correlation chromatography, a new technique applied to calibration in high performance liquid chromatography. Analytica Chimica Acta 181: 37-49. van der Moolen JN, Louwerse DJ, Poppe H and Smit HC (1995). Correlation capillary zone electrophoresis, a novel technique to decrease detection limits. Chromatographia, 40: 368. van der Moolen JN, Poppe H and Smit HC (1997) A micro machined injection device for CZE, Application to Correlation CZE. Analytical Chemistry 69: 4220-4225.

the stationary bed and is efficiently equilibrated with it by means of either hydrodynamic or turbulent mixing.

In earlier forms of liquid-liquid partition chromatography introduced by Martin and Synge, where one phase is retained in a porous matrix such as diatomaceous earth or cellulose, significant peak tailing is often seen and some analytes are lost by irreversible adsorption on the supporting matrix. In CCC, the stationary phase is retained by gravitational, inertial or capillary forces and adsorption is precluded by construction of the apparatus from polytetrafluoroethylene (PTFE) or other inert, usually polymeric, material. Thus analyte migration in CCC is determined only by its partition coefficient in the two-phase system and peaks are typically quite symmetrical.

CCC differs from countercurrent distribution (CCD) of the type introduced by Craig in the 1940s in that CCD is a discontinuous process based on attainment of partition equilibrium prior to phase transfer, whereas CCC is a continuous dynamic or steady-state process which characterizes all forms of chromato-graphy. Both CCC and CCD may employ the same solvent systems and both achieve separations based on the partition coefficient, but the apparatus

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Solar Panel Basics

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