The suggested procedure for spotting a sample on a thin‑layer chromatography (tlc) plate involves transferring a droplet of concentrated solution from a capillary onto the plate, allowing it to dry, then repeating the process over the existing spot. why is it advised to spot multiple times? to achieve a high concentration of sample in a large spot to facilitate visualization by having a higher compound concentration to fill the capillary almost instantly by capillary action to prevent the solvent in the developing chamber from evaporating