Principle of Soxhlet extraction
Soxhlet extraction is the most commonly used liquid-solid extraction method and is mainly suitable for the extraction and separation of solid samples.
Soxhlet extraction uses the solvent reflux and siphon principle to continuously extract the desired components from the solid mixture. When the liquid level of the solvent under reflux in the extraction cylinder exceeds the siphon of the Soxhlet extractor, the solvent in the extraction cylinder flows back into the round bottom flask, i.e., siphoning occurs. As the temperature increases, the reflux begins again. Before each siphon, the solid matter can be extracted by a pure hot solvent, and the extracted material is concentrated in the flask. The solvent is reused, the extraction time is shortened, and the extraction is improved. effectiveness.
Compared with the conventional solvent extraction method, the Soxhlet extraction method saves time and solvent, and improves the extraction efficiency, but is not suitable for the extraction of thermally unstable components.
The separation effect and enrichment factor are related to the nature of the sample, the extraction temperature, the extraction time, the nature and amount of the solvent. Generally, the substance to be tested is enriched in an organic solvent as much as possible while reducing the amount of extraction of impurities.