The working principle of Soxhlet extraction

The fat analyzer grinds the solid matter before extraction to increase the solid-liquid contact area. Then, put the solid matter in the filter paper bag and put it in the extractor. The lower end of the extractor is connected to the round bottom flask containing the leaching solvent (anhydrous ether or petroleum ether, etc.), and the reflux condenser is connected to it.
The round-bottom flask is heated to make the solvent boil. The vapor rises through the connecting pipe and enters the condenser. After being condensed, it drips into the extractor. The solvent contacts the solid for extraction. When the solvent level in the extractor reaches the highest point of the siphon , The solvent containing the extract is siphoned back to the flask, thus extracting a part of the substance. Then the leaching solvent in the round-bottom flask continues to evaporate, condense, leaching, and reflux, and repeat this process, so that the solid matter is continuously extracted by the pure leaching solvent, and the extracted matter is enriched in the flask.
Liquid-solid extraction uses solvents to achieve the purpose of extraction and separation by using solvents that have a large solubility for the required components in a solid mixture and a small solubility for impurities.

Siphon: Inverted U-shaped tubular structure.
Siphon effect: Siphon is a hydrodynamic phenomenon that uses the difference in liquid level to generate force, which can suck liquid without the aid of a pump. After the liquid at a higher position fills the siphon, the liquid in the container will continue to flow out to a lower position through the siphon. Under this structure, the liquid pressure difference between the two ends of the pipe can push the liquid over the highest point and discharge to the other end.

Crude fat: After the sample is extracted with anhydrous ether or petroleum ether and other solvents, the substance obtained by steaming off the solvent is called fat or crude fat in food analysis. Because in addition to fat, it also contains pigments and volatile oils, waxes, resins and other substances.


Post time: Mar-02-2022