Countercurrent chromatography in analytical chemistry (IUPAC technical report)

© 2009 IUPACCountercurrent chromatography (CCC) is a generic term covering all forms of liquid-liquid chromatography that use a support-free liquid stationary phase held in place by a simple centrifugal or complex centrifugal force field. Biphasic liquid systems are used with one liquid phase being the stationary phase and the other being the mobile phase. Although initiated almost 30 years ago, CCC lacked reliable columns. This is changing now, and the newly designed centrifuges appearing on the market make excellent CCC columns. This review focuses on the advantages of a liquid stationary phase and addresses the chromatographic theory of CCC. The main difference with classical liquid chromatography (LC) is the variable volume of the stationary phase. There are mainly two different ways to obtain a liquid stationary phase using centrifugal forces, the hydrostatic way and the hydrodynamic way. These two kinds of CCC columns are described and compared. The reported applications of CCC in analytical chemistry and comparison with other separation and enrichment methods show that the technique can be successfully used in the analysis of plants and other natural products, for the separation of biochemicals and pharmaceuticals, for the separation of alkaloids from medical herbs, in food analysis, etc. On the basis of the studies of the last two decades, recommendations are also given for the application of CCC in trace inorganic analysis and in radioanalytical chemistry

Chromatofocusing nonporous reversed-phase high-performance liquid chromatography/electrospray ionization time-of-flight mass spectrometry of proteins from human breast cancer whole cell lysates: a novel two-dimensional liquid chromatography/mass spectrometry method

A novel two-dimensional two-column liquid chromatography/mass spectrometry (LC/MS) technique is described in this work, where chromatofocusing (CF) has been coupled to nonporous reversed-phase (NPS-RP) HPLC to separate proteins from human breast epithelial whole cell lysates. The liquid fractions from NPS-RP-HPLC are readily amenable to direct on-line analysis using electrospray ionization orthogonal acceleration time-of-flight mass spectrometry (ESI-TOFMS). A key advantage of this technique is that proteins can be ‘peeled off’ in the liquid phase from the CF column according to their isoelectric points ( pI ) in the first chromatographic separation dimension. The NPS-RP-HPLC column further separates these pI -focused fractions based upon protein hydrophobicity as the second chromatographic dimension. The third dimension involves on-line molecular weight determination using ESI-TOFMS. As a result, this method has the potential to be fully automated. In addition, a 2-D protein map of pI versus molecular weight is generated, which is analogous to a 2-D gel image. Thus, this technique may provide a means to study differential expression of proteins from whole cell lysates. Copyright © 2001 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35081/1/227_ftp.pd

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Abstract Retention behavior of halogenated benzylamines on an ODS stationary phase was studied using phosphate buffer (20 mM , pH 2.0) / acetonitrile (95/5, v/v, %) as a mobile phase. The thermodynamic properties for the transfer of halogenated benzylamines from the mobile phase to the stationary phase were evaluated for understanding on the retention mechanism in the reversed−phase high−performance liquid chromatography. The data were analyzed to sufficiently confirm the possibility of enthalpy−entropy compensation (EEC). The EEC indicates that enthalpic gain for retention is canceled out to one half by the entropic loss, and that entropy−driven retention could take place without enthalpic contribution

Original scientific paper

Determination of inorganic anions in papermaking water

Acknowledgement to Reviewers of Chromatography in 2014

The editors of Chromatography would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2014:[...