chamber The automated multiple development chamber was designed for applications employing incremental multiple development with a decreasing solvent strength gradient, Fig. 8 [18,22,24]. The operating variables of layer conditioning, mobile phase composition for each development, solvent front migration distance,drying time, and the number of developments are entered into the computer-based control unit. Without further intervention the complete separation sequence is carried out. The layer remains in a fixed position and the mobile phase components are selected from up to five solvent bottles, mixed, and then added to the chamber. A sensor monitors the solvent front migration distance. At the selected distance, the development is stopped by draining the mobile phase from the chamber and removing solvent adsorbedby the layer by vacuum. A new sequence is then commenced until the complete program has been executed. Typically each development is 1–3 mm longer than the previous one and employs a solvent of lower solvent strength. The first few developments typically employ a strong solvent to primarily focus the sample zones.Subsequent developments are typically longer employing weaker solvents responsible for the separation. The number of developments required for a separation depends on the complexity of the mixture and the shape of the desired gradient profile, typically 10–30 developments requiring 1.5–4.5 h for completion are used.This time can be approximately halved using Lichrospher plates consisting of thin-layers (100 m) coated with spherical particles.The combination of the focusing effect and gradient development results in narrow bands with improved resolution (four-fold) and sample detect ability compared with a single development. This method is used primarily for the separation of complex mixtures containing components covering a wide polarity range. Due to the separation process, bands remain focused and sharp for all separation distances providing a higher zone capacity than observed in single-development methods.