Preparative (Prep) or purification chromatography is defined as the process of using chromatography to isolate a compound in a quantity and at a purity level sufficient for further experiments or processe. Preparative chromatography can be performed with an analytical column (and system) to produce a few micrograms of material, up to process scale, providing a ton quantities of sample, which use 1-m-long, 200-mm i.d columns. The larger the quantity of analyte required, the further the technique is removed from analytical chromatography, both in terms of scale and ideology; the bigger the scale, the more "nonchromatographic" parameters have to be considered.