Publisher Summary This chapter discusses simple to more sophisticated techniques based on liquid chromatography. Liquid chromatography is the laboratory-scale technique of choice for the isolation and purification of materials that cannot be handled by crystallization or simple distillation. The purpose of preparative-scale chromatography is the isolation of compounds with a specified purity and in amounts suitable for their intended application. This includes the isolation of materials for structural elucidation, biological or sensory evaluation, use as analytical standards, organic synthesis, or commerce. The scale of the process varies considerably, and includes laboratory, pilot plant, and process-scale operations. For structural elucidation and initial biological activity screening, 30–50 mg of pure substance is usually adequate; for being used as an analytical standard, >100 mg is required; for synthesis, gram quantities are needed; and at the production scale, kilograms and upward are possibly desirable. For the first three applications, separations can be handled in the laboratory, while for pilot plant and process-scale separations, special purpose equipment and facilities are usually required. In addition, process-scale separations are performed to satisfy economic factors, often of less significance for laboratory-scale separations. The process-scale chromatography is of considerable importance for the manufacture of high-value added products, such as pharmaceuticals, flavors and fragrances, and biotechnology products, where the rather high unit costs of purification are not considered prohibitive.