Chromotography

Question 1

What two ‘phases’ do all forms of chromatography have and what do they mean??

Answer 1

Stationary and mobile phases:

• Stationary phase= does not move and is normally a solid or a liquid substance supported on a substance
• Mobile phases= does move, normally liquid or gas

Question 2

How does TLC work??

Answer 2

Stationary phase= solid adsorbent substance on plastic/glass sheet
Mobile phase= the liquid you are analysing

The different components of the liquid have different affinities for the absorbent and bind with differing strengths to its surface. ADSORPTION is the process by which the solid silica holds different substances in the mixture to its surface, separating the different components by their affinity to bind.

Question 3

Whats the equation for interpreting the TLC plate / retention factor??

Answer 3

Distance moved by component / distance moved by solvent front.

This equation gives you a value that can be compared to given values to identify the components