Reflux hot dip method and circulating reflux method
The reflux method uses volatile organic solvents such as ethanol as the extraction solvent to heat and distill the leaching liquid, in which the volatile solvent is condensed after distillation, and then returned to the leaching device to continue participating in the extraction process, and the cycle is carried out until the active ingredient is fully extracted. This is the reflux extraction method. The reflux method can be divided into the reflux hot leaching method and the circulating reflux method.
Reflux hot dip method: putmedicinal materialsIn the extractor with the condensation system attached to the decoction piece, a solvent is added to immerse the surface of the drug layer, and after soaking for a certain period of time, it is heated to extract. The evaporated solvent is condensed and directly returned to the extractor. After the specified time, the reflux liquid is filtered out, and then a new solvent is added to continue the reflux process several times, and each reflux leaching liquid is combined, and then the solvent is distilled out to obtain the leaching concentrate for use.
Circulating reflux method: a small amount of powder can be extracted by a Soxhlet extractor, and a circulating reflux device is used in large-scale production. The medicinal herbs are placed in the leaching device, and the solvent is added to the leaching device from the storage tank. When the leaching liquid is filled with a siphon, it enters the evaporation tank to be heated and evaporated, and the generated solvent vapor enters the condenser. After condensation, it is refluxed into the liquid storage cylinder and flows into the leaching device again. This cycle is repeated, and the concentrated leaching liquid is obtained in the evaporation tank. After the leaching is completed, the leaching device is properly heated to evaporate the organic solvent in the residue, and it is condensed along the pipeline into the serpentine tube of the condenser and sent to the storage tank.
Process characteristics: In essence, the reflux method is a hot leaching method, but because of the recycling of solvents, the reflux method uses less solvent than the percolation method, and the leaching is more complete. Since the reflux extraction requires continuous heating and the leaching time is long, it is not suitable for the leaching of heat-sensitive active ingredients. Usually used for the leaching treatment of traditional Chinese medicine raw materials with hard texture and difficult extraction.
The difference between the reflux hot dip method and the reflux hot dip method is that the reflux hot dip method solvent can only be recycled, and the extracted solute is still in the leaching device and cannot be continuously updated; while the reflux cold dip method solvent can be recycled, and the solvent can be continuously updated. The destruction effect of the extracted solute by continuous heating can be partially overcome by using an appropriate evaporation device, such as a thin film evaporator.
