Chromatography, countercurrent

Interest in countercurrent chromatography was revived in an effort to overcome problems frequently encountered in adsorption or exclusion chromatography, which uses a solid support. Most prominent among these problems was the difficulty in resolving mixtures of sensitive or highly polar compounds. Irreversible adsorption onto the solid phase, solid phase catalyzed decomposition, especially with silica gel, and severe tailing are obstacles to the purification of such molecules. 

Liquid-liquid partition chromatography in the absence of a solid phase avoids these problems. Furthermore, as the mechanism of solute transport is partition- 

CCC is according to Conway (1989) a form of liquid-liquid partition chromatography, in which centrifugal or gravitational forces are employed to maintain one liquid phase in a coil or train of chambers stationary, while a stream of a second, immiscible phase is passed through the system in contact with the stationary liquid phase. Retention of the individual components of the sample to be analyzed depends only on their partition coefficients and the volume ratio of the two applied liquid phases. Since there is no porous support, adsorption and catalytic effects encountered with solid supports are avoided. 

One form of CCC, which has been sporadically applied to separate essential oils into fractions or in the ideal case into individual pure components, is droplet countercurrent chromatography (DCCC). The device, which has been developed by Tanimura et al. (1970), consists of 300 600 glass tubes, which are connected to each other in series with Te on tubing and lied with a stationary liquid. Separation is achieved by passing droplets of the mobile phase through the columns, thus distributing 

Handbook of Essential Oils Science, Technology, and Applications 

Ito and Bowman (1970) have described a liquid-liquid partition chromatographic system (without solid support), which involves a long helix of narrow-bore tubing with an inner diameter of less than 0.5 mm. When the coiled tube is filled with one phase of a two-phase system and fed with the other phase, phase interchange takes place in each turn of the coil, leaving a segment of the former phase as the stationary phase. Solutes present in either phase are consequently subjected to a multistep partition process. To demonstrate the capability of the method Ito and Bowman used a two-phase system of chloroform, glacial acetic acid, and 0.1 IV 

The gels used in molecular-sieve chromatography are made of cross-linked dextrans (Sephadex type), polyacrylamide, and agar and agarose (Bio-gel type). 

Rather extensive use of molecular-sieve chromatography has been made in the fractionation of protein mixtures, and methods for the purification of enzymes and other proteins often include a molecular-sieving step [enzyme mixtures Gelotte 

Flodin and Aspberg (1961) have reported a marked separation of oligosaccharides on a column of gel of small pore size. Ringertz (1960) has reported the fractionation of acid polysaccharides from mouse tumors on a Sephadex column. The fractions differed in several properties, including the type of amino sugar present. Tanaka (1966) has reported on the fractionation and isolation of acid mucopolysaccharides. 

Low-molecular-weight carbohydrate components of normal urine have been separated by Lundblad and Berggard (1962), Flodin et al. (1964), and Lee and Ballou 

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EXTRACTANT CONCENTRATION GRADIENT IN THE AMERICIUM(III) / CURIUM(III) SEPARATION BY COUNTERCURRENT CHROMATOGRAPHY... 

The acceptable separation of Am(III) and Cm(III) by countercurrent chromatography (CCC) was achieved using both isocratic elution, and a new approach to the creation of the reagent concentration gradient in the stationary phase [1]. This way allows reduce the experiment length. 

A. Berthold (Ed.), Countercurrent Chromatography (CCC). The Support-Free Liquid Stationary Phase, Elsevier, Amsterdam, 2002. ISBN 044450737X. 

Several chromatographic modes will be reviewed in this respect, and most will make use of a chiral support in order to bring about a separation, differing only in the technology employed. Only countercurrent chromatography is based on a liquid-liquid separation. 

Flash chromatography is widely employed for the purification of crude products obtained by synthesis at a research laboratory scale (several grams) or isolated as extracts from natural products or fermentations. The solid support is based on silica gel, and the mobile phase is usually a mixture of a hydrocarbon, such as hexane or heptane, with an organic modifier, e.g. ethyl acetate, driven by low pressure air. (Recently the comparison of flash chromatography with countercurrent chromatography (CCC), a technique particularly adapted to preparative purposes, has been studied for the separation of nonchiral compounds [90].)... 

Countercurrent chromatography (CCC) refers to a chromatographic technique which allows the separation of solutes in a two-phase solvent system subjected to a gravitational field. Two immiscible liquid phases, constituted by one or more solvents or solutions, are submitted to successive equilibria, where the solutes to be separated... 

Y. Ito, B. Mandava (Eds.), Countercurrent chromatography theory and practice, Chromato-graphie seienee Series, Vol. 44, Mareel Dekker, New York (1988). 

W. D. Conway (Ed.), Countercurrent Chromatography apparatus, theory and applications, VCH Publ., New York (1990). 

Vol. 132. High Speed Countercurrent Chromatography. Edited by Yoichiro Ito and Walter D. Conway... 

BAUMANN D, ADLER s and HAMBURGER M (2001) A simple isolation method for the major catechins in green tea nsing high-speed countercurrent chromatography , JNat Prod, 64 (3), 353-5. 

DEGENHARDT A, ENGELHARDT U H, LAKENBRINK 0 and WINTERHALTER P (2000) Preparative separation of polyphenols from tea by high-speed countercurrent chromatography , J Agric Food Chem, 48, 3425-30. 

Degenhardt, A., Knapp, H., and Winterhalter, P, Separation and purification of anthocyanins by high-speed countercurrent chromatography and screening for antioxidant activity, J. Agric. Food Chem., 48, 338, 2000. 

Conway, W.D. and Petroski, R.J., Modem Countercurrent Chromatography, ACS Symposium Series 593, American Chemical Society, Washington, 1995. 

Ito, Y. and Conway, W.D., High Speed Countercurrent Chromatography, Wiley Interscience, New York, 1996. 

Schwarz, M. et al.. Application of high-speed countercurrent chromatography to the... 

Salas, E. et al.. Isolation of flavanol-anthocyanin adducts by countercurrent chromatography, J. Chrom. ScL, 43, 488, 2005. 

Forthright isolation of standard substances from known sources may be achieved by analytical and/or semi-preparative HPLC. Although it appears promising with respect to obtainable pigment yields, countercurrent chromatography has been applied only once for red beets but lacked sufficient separation efficiency. "... 

Countercurrent Chromatography Theory and Practice, edited by N. Bhushan Man-dava and Yoichiro Ito... 

Countercurrent Chromatography, edited by Jean-Michel Menet and Didier Thiebaut... 

The comprehensive review by Gocan et al. [25] focused specifically on lipophilic-ity measurements by liquid chromatography, including reversed phase, thin-layer, micellar, RP-ion-pair and countercurrent chromatography. 

Countercurrent chromatography is particularly attractive for the preliminaury fractionation of complex mixj s prior to further... 

Berthod, A., Separation with a liquid stationary phase the countercurrent chromatography technique, Instr. Sci. Technol., 23(2), 75, 1995. 

Soxhlet extraction of the dry gum (250 g) serially with hexanes, ether, and methanol resulted in an activity rich ether fraction (600 mg, dried in vacuo) that was partitioned between CCI4 and 50% aqueous MeOH. The dried aqueous layer (300 mg) was applied directly to droplet countercurrent chromatography (DCC), CgHg/MeOH/CHC /H ... 

Balannec B. and Hotier G., From batch to countercurrent chromatography , in Preparative and Production Scale Chromatography, G. Ganetsos and P.E. Barker (Editors), Marcel Dekker, New York, 1993. 

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