Soxhlet extraction is a common method for solid and liquid extraction. It is mainly applied for the extraction and separation of solid samples.
The Soxhlet extraction uses the principle of backflow and siphon of the solvent, and make continuous extraction of the needed components in the solid mixture. When the liquid level of solvent which backflows in the extraction shell surpass the siphon of the Soxhlet extractor, the solvent will flow back to the round-bottom flask, and then the siphon happens.
As the temperature goes up, the backflow starts again. Before each time of the siphon, the solid matter can be extracted by the pure hot solvent and the extracted substances will be concentrated in the flask. At the same time, the solvent can be recycled. It reduces the extraction time and improves extraction efficiency.
In comparison with other common solvent extraction methods, the Soxhlet extraction saves time and solvent, and also improve the extraction efficiency. However, it is not suitable for the extraction of the hot and labile element.
The separation effect and concentration factor are related to the character of the sample, the extraction temperature, the extraction time and the character and dosage of solvent. In general, the sample should be concentrated in the organic solvent as far as possible.
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