Question

TLC plates could be made of different particle size of silica. If one used a smaller particle size of silica in the TLC plate, how would that effect the results of a TLC experiment?

Answer 1

The efficiency of a separation increases if the particles in the stationary phase are made smaller. This is because the solute can equilibrate more rapidly between the two phases. However, if the particles are made smaller, capillary action increases and it becomes more difficult to drain the column under gravity. The surface area of a particle is inversely proportional to the pore diameter, smaller-pore columns are desired because of their higher surface area, as long as the analytes are sufficiently small to easily enter the pores. The particle size controls column efficiency. The pore size controls the surface area. Retention is controlled primarily by the surface area thus; separations are very efficient because of the much smaller particle size of the stationary phase.