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How does thin-layer chromatography move sample components across a plate?
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In thin-layer chromatography, sample components are moved across a plate through the following process:
- Application: The sample mixture is deposited as a spot near one end of a plate coated with a thin layer of a solid adsorbent, such as silica gel or alumina.12
- Mobile Phase Migration: The plate is placed vertically in a shallow reservoir containing a suitable solvent. This solvent acts as the mobile phase and travels up the plate by capillary action.12
- Separation: As the solvent moves upward, it dissolves the sample, transporting its components along the plate. The components separate because they have different degrees of attachment to the stationary adsorbent coating; substances that interact more strongly with the adsorbent move more slowly, while those with less affinity move more rapidly.12
This differential migration allows the components to reach distinct positions on the plate, where they can be identified after the solvent evaporates.12