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What's
the purpose of chromatography
In short, chromatography is a method of separating and purifying
compound mixtures.
For example,
after a reaction has completed your product may contain impurities
such as unreacted starting materials and unwanted side products.
One of the most common ways to purify the substance is through
chromatography.
Theory
behind chromatography
There
are several different types of chromatography. Four common
types of chromatography (those discussed in this guide) include:
- Thin-layer
chromatography (TLC)
- Column
(or Flash) chromatography
- Gas
chromatography (GC)
- Liquid
chromatography
All of
these chromatography methods operate on the same basic principle.
That is, the impure mixture is passed through a stationary
phase. Every different molecule will have a different attraction
to the stationary phase. Molecules that are highly attracted
to the stationary phase will "stick" to the stationary
phase and take a long time to pass through; other molecules
will have only weak attractions to the stationary phase and
will pass through quickly. Molecules are separated by the
fact that they travel through the stationary phase at different
rates. A brief animation is shown in the figure below illustrates
this point.
 Proceed
to Thin-Layer Chromatography (TLC)
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