Transient mobile phase environments created by in|ectlng solvent plugs of varying composition are shown to selectively elute compounds according to their chemical properties. With several organic dyestuffs as model solutes, weakly acidic, strongly acidic, and neutral substances were sequentially eluted In a series of subchromatograms based on pH, Ion-pair competition, and hydrophobic Interaction mechanisms, respectively. Elution with both Isocratlc plugs and with pluggenerated gradients Is described. The use of transparent columns allowed solute bands to be viewed during the separation process, and the potential for on-column detection and laser scanning Is discussed.