Soxhlet extractor

piece of laboratory apparatus. It was originally designed for the extraction of a lipid from a solid material, is used when the desired compound has a limited solubility in a solvent, and the impurity is insoluble in that solvent

A Soxhlet extractor is a kind of laboratory equipment. It is made of glass. Franz von Soxhlet invented it in 1879. It has a flask, an extraction chamber, and a condenser. It can be used for solid-liquid extractions.

Drawing of a Soxhlet extractor
1: Stirrer 2: Still pot 3: Distillation path 4: Thimble 5: Solid 6: Siphon top 7: Siphon exit 8: Expansion adapter 9: Condenser 10: Cooling water in 11: Cooling water out
Animation showing how a Soxhlet extractor works

In this discontinuous extraction process, the extraction solvent inside the boiling flask is evaporated and re-condensed in the distillation column above. It then falls down onto the solid material requiring extraction. The chamber containing the solid material is connected to the boiling flask below by a syphoning mechanism seen in the Pythagorean cup, which allows the chamber to fill to a point, at which it will empty its contents and start to fill again and the extracted compounds will accumulate in the boiling flask below.


Chemists use it to remove a material from a solid. It is useful when removing materials that do not dissolve well in any solvent. Chemists use a solvent such as ether or alcohol in the extractor. The Soxhlet extractor applies the solvent repeatedly to the solid until enough of the material dissolves.

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