chromatography

More can be found in module 05, chapter 4 about methods of separation

Chromatography is methode of analysis, used to separate mixtures; so you can investigate which substance you have, and on top of that: you can find and separate the different components.
Here we have two phases: When a certain colorant has big affinity to the mobile phase, then that colorant will dislocate easy and displace itself for a long distance; this colorant will move further than another.

Definition:
Chromatography is a method of separation based on (the difference in) the affinity of the investigated substance(s) relative to the two phases, a mobile phase and a fixed phase.

The concept/name 'chromatography' comes from the fact that this method first was used for separation of colorants only, gained from extraction of plant material.
Now there are many more techniques, also to find colorless substances; but the name 'chromatography' was maintained.
Apart from the colorants, we can investigate and separate:
  1. organic and inorganic molecules
  2. many kinds of ions
  3. biologically active substances, like proteins, nucleic acids and viruses.

As said, chromatography works with two phases. One of these phases is the stationary or fixed phase; it remains on its fixed location. the other phase, the mobile phase moves through that fixed phase; there is intensive contact between the two phases. The substance(s) to investigate were put somewhere on the fixed phase, and must divide itself over the fixed and passing mobile phase.

The fixed phase can be (s) or (l).
The mobile phase can be (l) or (g).
Thus you can distinguish four chromatographic techniques:
fixed
phase
(s)
(l)
mobile
phase
(l)
 (s) + (l) (l) + (l)
(g)
 (s) + (g) (l) + (g)


att.:
A so called 'carrier' is needed when the fixed phase is (l).

There are different chromatographic methods, like:
  1. Paper chromatography
  2. Column chromatography
  3. Gas chromatography