Question

Suppose a graig tube assembly has been chilled in an ice bath, why must the filtration step be performed quickly?

In TLC on alumina or silica, there is no stationary liquid phase as there is in GLC. What sort of property causes components to be "retained" by the substrate i.e. what is the physical basis for the separations which are observed?

Answer 1

After the sample has been applied on the plate, a solvent or solvent mixture (known as the mobile phase) is drawn up the plate via capillary action. Because different analytes ascend the TLC plate at different rates, separation is achieved. The mobile phase has different properties than the stationary phase.

Capillary action (sometimes capillarity, capillary motion, or wicking) is the ability of a liquid to flow in narrow spaces without the assistance of, or even in opposition to, external forces like gravity.