Abstract: A method of extracting a substance comprising the steps of: placing a substrate on which a substance has been adsorbed into a container; feeding a solvent into the container whilst restricting its exit to achieve a predetermined pressure of the solvent in the container, wherein the solvent has a critical point and the predetermined pressure is above the critical point of the solvent; releasing the solvent and an extract comprising extracted substances into a separator; reducing the temperature and pressure in the separator to remove a gaseous portion of the solvent from the extract; collecting the extract remaining from the separator.