Published on 19-12-2017

The Soxhlet extractor is designed for exhaustive solvent extraction – the extraction of as much soluble material as possible from a sample. Only a small amount of solvent is required to achieve a high yield, as the solvent is repeatedly recycled. This is especially effective for low-yield botanicals, or aromatic compounds with low solubility.

During extraction, the solvent boils and its vapour passes through the distillation arm of the Soxhlet extractor. It then condenses to a liquid in the condenser, and drips down into the main chamber of the extractor. As the main chamber fills up, the botanical material soaks in the solvent, and soluble materials are drawn out. Once a threshold volume of solvent is reached in the extractor, all the solvent, containing extracted compounds, drains into the boiling flask. The cycle is repeated, using the same solvent, and leaving anything already extracted behind in the boiling flask.

The cycling can be repeated for as long as desired, until absolutely all soluble substances have been extracted. The Soxhlet thimbles we provide can hold approximately 30 g of botanicals, depending on their density.

Ethanol is a safe and effect solvent for Soxhlet extraction, but if a purer absolute is desired, a non-polar solvent like hexane may also be used. However, for the purposes of ease and safety, ethanol is generally recommended, especially for those new to Soxhlet extraction. Only about 150 ml of ethanol is required per extraction.

Soxhlet extraction was initially developed by Franz Ritter von Soxhlet, to extract lipids from milk solids. It has far broader contemporary uses, however, including in the biochemistry, food, and oil industries.

Depending on the solvent used, extremely potent absolutes or extracts can be prepared, allowing the equivalent of weeks’ worth of maceration to be yielded in just a few hours. Only a few drops of these extracts may be needed to flavour, and colour, a full bottle of spirit.