Partition vs Adsorption
Definition
Partition chromatography separates by differential solubility between two liquid phases (GLC, reversed-phase HPLC). Adsorption chromatography separates by surface binding to a solid (classical TLC on silica).
- Partition mechanism
- Differential solubility between two liquid phases
- Adsorption mechanism
- Surface binding to a solid
- Partition examples
- GLC, reversed-phase HPLC
- Adsorption example
- Classical TLC on silica
Common questions
How can you tell whether a separation relies on partition or adsorption?+
Partition systems use a liquid stationary phase coated on or bonded to a support, so solutes distribute between two liquids. Adsorption systems use an active solid surface, so solutes compete for binding sites on it.
Why does this distinction matter for method selection?+
Adsorption separations are more sensitive to trace polar impurities and moisture on the solid surface, while partition separations tend to give more reproducible retention behaviour across a run.
Related terms
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- FID
- Flame ionisation detector. A hydrogen-air flame ionises C-H bond containing analytes and a collector electrode reads the ion current. Near-universal for organic...
- Isocratic vs Gradient Elution
- Isocratic means the mobile-phase composition stays constant through the run; simple, reproducible, but limited resolving power for wide-polarity mixtures. Gradient means the...
- Mobile Phase
- The solvent or mixture that flows over the stationary phase and carries analytes along. Polarity, viscosity and volatility set the separation; switching...
- MSD
- Mass Selective Detector. GC-MS or LC-MS detector that identifies analytes by mass spectrum. The confirmation standard for drug and toxicology casework.
- Plate Theory
- Model that treats a column as a series of theoretical plates. The Height Equivalent to a Theoretical Plate (HETP) measures column efficiency;...
- Rf Value
- The retention factor, defined as the distance the spot travels divided by the distance the solvent front travels on the same plate....
- Stationary Phase
- The immobile material the mixture flows past. In paper it is water inside cellulose fibres; in classical column work and TLC it...