Full report on chromatology?

Answer 1

I'm not sure this is the best place for a long report on chromatography, mostly because a very complete report would be something book-sized, if you know what I mean. But I can at least summarize a bit, and point you in the direction of more details, if you like.

Chromatography is a frequently used technique in chemistry to separate out the contents of a mixed solution for the purposes of purification, differential analysis, and so on. It is useful in analysis of unknowns (GC/MS - a gas chromatograph which feeds directly into a mass spectrometer - is quite common) and also for isolating materials (some phamaceutical companies have HUGE seperations columns to get large volumes of product all at once).

The basic principle on which chromatography works is that even in a solution, some molecules may be made to move faster than others. This is accomplished either through obstacles that either block or attact solutes differentially, or though applied forces which work on solutes differentially.

A standard example would be a column filled with a silica gel solution. The material you want to separate out is poured in the top, followed by water to keep the volume constant. The numerous small beads provide a huge surface area for the highly polar gel to slow down polar molecules down with. So as you take different samples over time from the bottom, you will tend to get a gradient of non-polar, less-polar, and then most-polar last.

You can see how using different stationary phases in the column could produce all kinds of different kinds of gradients based on size, affinity for specific bound molecules, solubility, or any number of other properties. In some cases the separations are even visible if differently affected molecules are of different colours! This is sometimes done on purpose with indicators, too, so you can capture the 'right' sample when you're collecting at the bottom.

The first link below has an encyclopedia definition of chromatography, the second a collection of online books about chromatography. Hope that helps!

Answer 2

... care to elaborate...?