Essential oils (also called volatile oils) generally extracted by distillation from plants are hydrophobic liquids containing volatile aromatic compounds. The essential oils are widely used in perfumes, cosmetics as well as in food and drink as flavor additives. Some essential oils show multiple pharmacological activities and have been considered as the major active fractions of herbal medicines [1–3]. Preparative separation of the volatile components is very important not only for the quality control of the crude herbs and the products containing the essential oil but also for the bio-evaluation. However, preparative separation of these pure volatile components is a challenge because of their structural similarity, strongly hydrophobic properties and poor stability. Column.
