Thin Layer Chromatography - Continuous Plate Development
Continuous Plate Development
The normal development of a thin layer plate is restricted by its physical dimensions but a continuous development procedure has been developed employing special equipment. An example of an apparatus used for the continuous development of a thin layer plate is shown in figure 8. The plate is held inverted in a horizontal position so that the layer of stationary phase faces downwards and rests on a second glass cover plate. A wick is employed to transport the solvent(s) from the reservoir to the stationary phase coating that is now sandwiched between the two glass plates as shown on the left-hand side of figure 8. The whole apparatus is located in a suitable chamber to avoid solvent evaporation from the reservoir. The solvent percolates along the plate driven by surface tension forces until it reaches the end of the plate.
A small area at the end of the plate is left exposed (see right hand side of figure 8) and heated electrically so that the solvent is continuously as it arrives. In this manner development can be continued for any length of time and the system now look a lot like an LC column of lamina shape. The value of this technique seems to be a little questionable, as its intent appears to be to simulate an LC column, in which case, it would be far better to use an LC column in a normal manner in the first place.