chamberThe automated multiple development chamber was designedfor applications employing incremental multiple developmentwith a decreasing solvent strength gradient, Fig. 8 [18,22,24]. Theoperating variables of layer conditioning, mobile phase compo-sition for each development, solvent front migration distance,drying time, and the number of developments are entered intothe computer-based control unit. Without further intervention thecomplete separation sequence is carried out. The layer remains in afixed position and the mobile phase components are selected fromup to five solvent bottles, mixed, and then added to the cham-ber. A sensor monitors the solvent front migration distance. Atthe selected distance, the development is stopped by draining themobile phase from the chamber and removing solvent adsorbedby the layer by vacuum. A new sequence is then commenced untilthe complete program has been executed. Typically each devel-opment is 1–3 mm longer than the previous one and employs asolvent of lower solvent strength. The first few developments typ-ically employ a strong solvent to primarily focus the sample zones.Subsequent developments are typically longer employing weakersolvents responsible for the separation. The number of develop-ments required for a separation depends on the complexity of themixture and the shape of the desired gradient profile, typically10–30 developments requiring 1.5–4.5 h for completion are used.This time can be approximately halved using Lichrospher plates