Thin Layer Chromatography - Two-Dimensional TLC 1
A two-dimensional forced-flow TLC plate arrangement is shown in figure 10.
Two-dimensional TLC can provide improved resolution and consequently is very advantageous in the separation of complex mixtures. The apparatus for two-dimensional TLC is very similar to that used for the forced-flow procedure depicted in figure 8 except that a square plate is used and there are two solvent inlets and two solvent outlets. The sample is initially spotted on the top right-hand corner of the plate and the plate developed by forced flow downwards. This produces a series of solute bands or spots down the right-hand side of the plate. After a predetermined time, the vertical downward flow is stopped and the plate is developed employing a different second solvent that is passed by forced-flow from right to left across the plate. This produces a separation similar to that depicted in figure 11.