The separation chamber contains four main components; a holding unit, a hydraulic unit, a tray-like layer cassette, and an attached drain valve. The thin-layer plate is placed in the cassette and then inserted into the separation chamber,which automatically seals the layer by the pressurized plastic sheet. Different cassettes facilitate the use of 20 cm-long plates of different widths for linear development (effective plate lengthbetween the inlet and outlet troughs is 18.3 cm), bi-directional linear development (mobile phase is applied at the center and flows simultaneously in both directions toward opposite edges of thelayer; two-dimensional development (sequential development of the layer in orthogonal directions with drying of the layer between