How does thin-layer chromatography separate substances on a flat plate?

Thin-layer chromatography (TLC) separates chemical substances by utilizing a stationary phase and a mobile phase. The stationary phase consists of a thin layer of a finely ground adsorbent, such as silica gel or alumina, coated onto a flat glass or plastic plate.12

To perform the separation, a sample is deposited as a spot near one end of the plate. The plate is then placed vertically in a reservoir containing a suitable solvent, which acts as the mobile phase. As the solvent travels up the plate via capillary action, it dissolves the sample and transports its components.12

Separation occurs because each component of the mixture interacts differently with the stationary phase and the mobile phase. Components that have a stronger affinity for the stationary phase are held back, while those with a greater affinity for the mobile phase travel further up the plate. This differential migration results in the components reaching different positions on the plate, allowing for their identification once the solvent evaporates.231