spotted plate 
in tank with
mobile phase
mobile phase
creeping up 
fully developedIn thin layer chromatography the stationary phase is a layer of silica on an aluminium backing plate.
The diagram shows a thin layer plate where a mixture has been applied at the left side and a pure substance at the right.
The separation is accomplished by passing a
mobile phase (solvent) over the stationary phase.
In thin layer chromatography, the
plate is
immersed in a vessel containing the
solvent to a depth
no higher than the level at which the plate was
spotted.
As the solvent moves through the spot, the
mixture is
separated because
some components are
more attracted to the stationary phase than others.
Think about:
The
substance is less attracted to the stationary phase.
Substances that move to the
same extent may be the
same.
In general, because the
stationary phase is polar, more
polar substances are
retarded to a
greater extent.
Think about:
The substance giving the
spot is more polar.