... and the impurities whereas distillation exploits differences in volatility. Adsorption chromatography separates and purifies compounds according to their adsorption to the chromatographic material, which to a good approximation is related to the polarity of the compounds. Major purification techniques relevant to the laboratory include extraction, crystallisation, distillation and chromatography in all their various forms. Extraction in the chemical sense means 'pulling out' a compound from one phase to another, usually from a liquid or a solid to another liquid. In the organic laboratory, the most common process involves the extraction of an organic compound from one liquid phase to another. The two liquid phases are usually an aqueous solution and an organic solvent, and the technique is known as liquid-liquid extraction or more commonly, as extraction. A simple extraction is often used in the work-up of an organic reaction mixture, but extraction can also be used to separate and purify organic compounds. ...

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