Chromatographic animations

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Principle of Chromatography

The following examples explain the chromatographic principle and the difference between chromatography and two-phase extraction.


By ordinary two-phase extraction we can get an enrichment of the molecules in different phases, but we will not achieve complete separation

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Repeated extractions

In this example one of the phases is moving relative to the other. Other conditions are identical to the example above. The moving phase is the mobile phase. The two compounds will move through the system with a velocity that is equal to the mobile phase velocity (u) multiplied with the fraction of the compound that is in the mobile phase (0.25 for the red molecules and 0.5 for the blue molecules). Because the molecules move with different average velocity there will be a partial separation in the direction of the flow.

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Double mixing frequency

In this example the conditions are the same as above, except that the frequency of mixing is doubled. There is now complete separation of the molecules. The more often the molecules can exchange between the phases, the better the separation. The exchange between the phases should therefore be maximized.

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Chromatography is similar to the examples above. The difference is that the phases are not mixed and that the force that lead to exchange between the phases is diffusion.

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