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Adsorption is the attachment of particles to a surface, while partition is distribution between two phases by solubility. Free notes and 6 questions answered.
Chromatography Types: TLC, CC & GC (Part 2/4) is part of Chromatography (A-level only) in A Level AQA Chemistry.
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Adsorption is the attachment of particles to a surface, while partition is distribution between two phases by solubility. Free notes and 6 questions answered.
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Use this lesson to stay inside Chromatography (A-level only) while connecting the detail back to the wider Organic chemistry topic.
Read the core explanations from Chromatography Types: TLC, CC & GC (Part 2/4) before testing yourself from memory.
Chromatographic separation is often explained using two linked ideas: adsorption and partition. In TLC and column chromatography, substances may adsorb to the solid stationary phase to different extents. In GC, substances partition between the carrier gas and the stationary phase inside the column.
Worked example: Explaining Different Chromatography Outcomes
Why might one compound move quickly in TLC but have a long retention time in GC?
Answer: Chromatographic behaviour depends on the phases and conditions of the specific method, so a substance can behave differently in TLC and GC.
| Technique | Main separation language | Useful output |
|---|---|---|
| TLC | adsorption / relative movement on a plate | Rf value and spot pattern |
| Column chromatography | different movement through packed stationary phase | separate fractions |
| GC | partition / retention in the column | retention time and peak area |
At A level, the key is not to memorise the words adsorption and partition in isolation. It is to use them to explain why the observed Rf value, retention time, or peak area makes sense for the method being used.
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Move to the related lessons or back to the topic page when you need the wider sequence before exam-style practice.
In TLC, compounds interact with the solid stationary phase, such as silica, and adsorb to it to different extents. Movement depends on attraction to the stationary phase versus solubility in the solvent, so a compound that interacts weakly with the stationary phase moves quickly.
Adsorption is the attachment of particles to a surface. In TLC and column chromatography, substances adsorb to the solid stationary phase, such as silica, to different extents, which is why separation happens.
Partition is the distribution of a substance between two phases according to how soluble it is in each one. In GC, a compound divides its time between the carrier gas and the stationary phase inside the column, which sets its retention time.
Chromatographic behaviour depends on the phases and conditions of the specific method. A compound can move quickly in TLC if it interacts weakly with the stationary phase under that solvent system, yet partition strongly into the stationary phase inside a GC column.
TLC gives an Rf value and a spot pattern on a plate. Column chromatography gives separate fractions as substances move differently through the packed stationary phase. GC gives a retention time and a peak area for each component.
Adsorption is the attachment of particles to a surface, such as molecules interacting with silica in TLC. Partition is the distribution of a substance between two phases according to how soluble it is in each, such as a compound dividing its time between the carrier gas and stationary phase in GC.