Thin-Layer Chromatography:
- Used to analyse small samples using separation
- There are 2 phases in the process: stationary and mobile phase
Stationary phase:
- This phase is commonly a thin metal sheet coated in alumina (Al2O3 ) or silica (SiO2 )
- The solute molecules adsorb onto the surface
- Depending on the strength of interactions with the stationary phase, the separated components will
travel particular distances through the plate
- The more they interact with the stationary phase, the more they will 'stick to it
Mobile phase:
- It is a polar or nonpolar liquid(solvent) or gas that carries components of the compound being
investigated
- Flows over the stationary phase
- Polar solvents - water or alcohol
- It is easy to identify coloured components of the sample
- can examine the plate under UV light using ninhydrin to identify uncoloured components
TLC steps:
Step 1: Prepare a beaker with a small quantity of solvent
Step 2: Draw a baseline on the TLC plate
Step 3: Place a spot of a pure (reference) compound on the left of the baseline, and a spot of the sample to
be analysed on the right and allow it to dry. (the pure compound will identify the mixture of compounds in
the sample)
Step 4: Place the plate inside the beaker with solvent (make sure the baseline is lower than the level of the
solvent) and place a lid to cover the beaker.
Step 5: As the solvent reaches the top, remove the plate and draw another line where the solvent has
reached, this is called the solvent front.
values measured from baseline
*The less polar components travel FURTHER up the plate:
- Their Rf values are higher than those closer to the baseline
- They are more soluble in the mobile phase and get carried forwards with the solvent
*More polar components do not travel far as they are more attracted to the polar stationary phase.
Knowing the Rf values of compounds helps to compare the polarity of molecules.
Gas/Liquid Chromatography:
GLC is used for analysing gases, volatile liquids and solids in their vapour form.
Stationary phase:
- Uses a column as a stationary phase
- A non-polar, long-chain, non-volatile hydrocarbon with a high boiling point is mounted onto a solid
support
- Small silica particles can be packed into a glass column to offer a large surface area
Mobile phase:
- Used to analyse small samples using separation
- There are 2 phases in the process: stationary and mobile phase
Stationary phase:
- This phase is commonly a thin metal sheet coated in alumina (Al2O3 ) or silica (SiO2 )
- The solute molecules adsorb onto the surface
- Depending on the strength of interactions with the stationary phase, the separated components will
travel particular distances through the plate
- The more they interact with the stationary phase, the more they will 'stick to it
Mobile phase:
- It is a polar or nonpolar liquid(solvent) or gas that carries components of the compound being
investigated
- Flows over the stationary phase
- Polar solvents - water or alcohol
- It is easy to identify coloured components of the sample
- can examine the plate under UV light using ninhydrin to identify uncoloured components
TLC steps:
Step 1: Prepare a beaker with a small quantity of solvent
Step 2: Draw a baseline on the TLC plate
Step 3: Place a spot of a pure (reference) compound on the left of the baseline, and a spot of the sample to
be analysed on the right and allow it to dry. (the pure compound will identify the mixture of compounds in
the sample)
Step 4: Place the plate inside the beaker with solvent (make sure the baseline is lower than the level of the
solvent) and place a lid to cover the beaker.
Step 5: As the solvent reaches the top, remove the plate and draw another line where the solvent has
reached, this is called the solvent front.
values measured from baseline
*The less polar components travel FURTHER up the plate:
- Their Rf values are higher than those closer to the baseline
- They are more soluble in the mobile phase and get carried forwards with the solvent
*More polar components do not travel far as they are more attracted to the polar stationary phase.
Knowing the Rf values of compounds helps to compare the polarity of molecules.
Gas/Liquid Chromatography:
GLC is used for analysing gases, volatile liquids and solids in their vapour form.
Stationary phase:
- Uses a column as a stationary phase
- A non-polar, long-chain, non-volatile hydrocarbon with a high boiling point is mounted onto a solid
support
- Small silica particles can be packed into a glass column to offer a large surface area
Mobile phase:
