As the components of the mixture are separated, they begin to form moving bands (or zones),with each band containing a single component . If the column is long enough and the other parameters (column diameter , adsorbent, solvent , and flow rate) are correctly chosen , the bands separate from one another, leaving gaps of pure solvent in between . As each band (solvent and solute)passes out from the bottom of the column , it can be collected before the next band arrives.If the parameters mentioned are poorly chosen, the collected before the next band arrives. If the parameters mentioned are poorly chosen, the various bands either overlap or coincide , in which case either a poorly chosen, the various bands either overlap or coincide , in which case either a poor separation or no separation is the result.