Thin Layer Chromatography - Thin Layer Chromatography Chambers 1




Figure 3. The Normal Method of Thin Layer Plate Development


In its simplest form, the developing chamber consists of a round or square glass jar fitted with a glass cap. Sufficient solvent mixture is placed in the chamber to raise the mobile phase level to about a centimeter from the base and is left for a while to allow the air space above the solvent to become saturated with solvent vapor. The plate is then quickly placed in the chamber with the minimum of air disturbance and the cap rapidly put back. The end of the plate, where the samples have been placed, is made to dip into the solvent. It is important to ensure that the sample spots themselves are not at, or below, the surface of the solvent mixture when placed in the jar or they will be washed away from the plate. The solvent must rise up the plate and pass over the sample spots to develop the plate satisfactorily. To improve air space saturation, the walls (or part of the walls) of the chamber are sometimes lined with filter paper that acts as a wick to soak up the developing solvent and to provide a greater surface area for evaporation. The use of a paper wick is depicted on the right-hand side of figure 3.