Why use Soxhlet extractor to extract caffeine from tea? Why not use the general reflux condensing device?

Because caffeine begins to sublimate at 100℃, it takes a long time to heat it with a general reflux condensing device, and caffeine sublimates and escapes from the solution, and finally it cannot be obtained. Soxhlet extractor uses concentrated ethanol to extract, and the sublimation of caffeine is greatly reduced.

Although in the absence of Soxhlet extractor, reflux condensation device can be used. However, the solvent consumption of general reflux condensing device is large, and the extraction effect of Bison extractor is poor. In addition, reflux will also cause the loss of solvent.

Extended data

The principle of Soxhlet extractor

The solvent reflux and siphon mechanism are used to continuously extract the required components in the solid mixture. When the liquid level of the solvent flowing back to the extraction cylinder exceeds the siphon of the Soxhlet extractor, the solvent in the extraction cylinder flows back to the round bottom flask, that is, siphon occurs.

With the increase of temperature, reflux began again. Before each siphon, solid substances can be extracted with pure hot solvent, and the solvent is reused, which shortens the extraction time, so the extraction efficiency is high.

When extracting, wrap the sample to be detected with degreased filter paper and put it into the extraction tube. Add petroleum ether into the extraction bottle, heat the extraction bottle, evaporate the petroleum ether, rise from the connecting pipe to the condenser, and drop the condensate into the extraction pipe to extract the lipid substances in the sample.

The liquid level of petroleum ether in the pipeline to be extracted reaches a certain height, and the petroleum ether dissolved with crude fat flows into the extraction bottle through the siphon. The petroleum ether flowing into the extraction bottle is continuously heated, gasified, lifted, condensed, dripped into the extraction tube, and so on until the extraction is completed.