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Written by The Clever Chromatrographer
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Sunday, 11 October 2009 08:18 |
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Ironically, a few weeks after I thought I had found an article that proposed single-phase CCC, I really did discover such a publication. The article is entitled “Peak Shape and Dispersion Behavior of Solutes in Counter-Current Chromatography with a Single Phase” and published in JCA 1216, on pages 6789-6795. The article explores how different solute-solvent combinations behave in a countercurrent chromatograph. Apparently, a laminar flow model predicts that the linear velocity of the solvent is highest in the center of tube and steadily decreases as it becomes closer to the walls of the tubing. Solute substances, therefore, become distributed between the fast moving center and the slow moving periphery as they move through the column. The diffusion of substances can be observed in the shape of their elution peaks. The better the diffusion the sharper the peak. Substances with poor diffusion tend to give broad, lumpy peaks. Ostensibly, compounds with different diffusion rates could be separated in such as column. This is, evidently, the concept behind “wide-bore hydrodynamic chromatography.” You do not need a CCC machine to pump a solution through a length of PTFE tubing. However, if you have a CCC instrument handy, the rotation of the coils acts to increase diffusion and sharpen peaks. Unfortunately, it does this for all solutes so the single-phase CCC as a separation technique still needs some work. The study does illuminate the importance the radial mass transfer in any CCC operation. All in all, the column composition and shape most likely has a profound effect on behavior of compounds in a CCC tube.
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Last Updated on Sunday, 11 October 2009 08:22 |
