Preparative Layer Chromatography multiple development

Other variations have been described by Szepesi and Nyiredy (1996) and Nyiredy (1996). Incremental multiple development (IMD) (Szabady et al., 1995 and 1997) involves rechromatography with the same composition mobile phase for distances that increase, usually by the same amount (linearly). If development occurs in the same direction with the same distance but different mobile phases having distinctive strength and selectivity, the method is termed gradient multiple development (GMD) this method most significantly increases the separation capacity of the system. In bivariate multiple development, the development distance and mobile phase composition are varied simultaneously for successive runs this method, which is effective for samples of differing polarity, has been used especially for preparative layer chromatography plates. 

The optimum extraction conditions are obtained by experiments as follows extraction solvent, the ratio of material to solvent (W/V), extraction temperature, extraction time, and elution or development solvents for chromatographic column or thin-layer chromatography. The sample preparation procedure, either one-step extraction or multiple-step extraction, needs to be carefully tried according to the analytical procedure subsequently used. 

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