The Introduction to Soxhlet Extraction
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 follows the principle of backflow and siphon of the solvent, and makes continuous extraction of the needed components in the solid and liquid 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, while the solvent can be recycled. It reduces the extraction time and largely improves extraction efficiency.
In comparison with other common solvent extraction methods, the Soxhlet extraction minimizes separation time and solvents needed, and also improves the extraction efficiency. However, it can not be applied for the extraction of the hot or labile element.
The extraction effect and concentration factor are relative to the characteristics of the sample, the extraction temperature, the extraction time and the characteristics and dosage of solvent. In general, the sample should be concentrated in the organic solvent as far as possible.
Notes when using a Soxhlet extractor:
1. Temperature: the set temperature of the extraction heating is adjusted according to the temperature of the room temperature. In winter, the glass tube must be prevented from icing.
2. Heating: when heating, it is necessary to inject distilled water to prevent the electric heating tube from being damaged.
3. Extraction: pay attention to the water level during extraction, and replenish distilled water in time when the water level is low.
4. Installation: The installed equipment should be neat and tidy, and the plane of each component of the instrument should be parallel or vertical.