Microwave extraction is a newly developed new technology that uses microwave energy to increase extraction rate. Its principle is that in the microwave field, the difference in the ability to absorb microwaves causes certain regions of the matrix material or certain components in the extraction system to be selectively heated, thereby separating the extracted material from the matrix or system into the medium. Among the extracting agents with small electric constant and relatively poor microwave absorption capacity, microwave extraction has the characteristics of simple equipment, wide application range, high extraction efficiency, good reproducibility, time saving, reagent saving and low pollution. At present, in addition to being mainly used for environmental sample pretreatment, it is also used in the fields of biochemistry, food, industrial analysis and natural product extraction. In China, there are few reports on the application of microwave extraction technology in the extraction of Chinese herbal medicine.

The mechanism of microwave extraction can be considered from two aspects. On the one hand, the microwave radiation process is a high-frequency electromagnetic wave that penetrates the extraction medium and reaches the internal vascular bundle and the glandular system of the material. Due to the absorption of microwave energy, the internal temperature of the cells rises rapidly, causing the internal pressure of the cells to exceed the capacity of the cell wall to expand and the cells to rupture. The active components in the cells flow freely, and the extraction medium captures and dissolves at a lower temperature. The extracted material is obtained by further filtration and separation. On the other hand, the electromagnetic field generated by the microwave accelerates the diffusion rate of the extracted component to the interface of the extraction solvent. When water is used as the solvent, the water molecules rotate at high speed to become an excited state under the microwave field, which is a high energy unstable state, or Water molecules vaporize to enhance the driving force of the extracted components; or the water molecules themselves release energy back to the ground state, the released energy is transferred to other substances, accelerates its thermal motion, and shortens the molecules of the extracted components from the inside of the material to the extraction solvent. The time of the interface increases the extraction rate several times, while also reducing the extraction temperature to maximize the quality of the extraction.

A further document is described as follows: Since the frequency of the microwave is related to the frequency of molecular rotation, the microwave energy is a non-ionizing radiant energy that causes molecular motion caused by ion migration and dipole rotation. When it acts on the molecule, it promotes the rotational motion of the molecule. If the molecule has a certain polarity at this time, it will generate instantaneous polarization under the action of microwave electromagnetic field, and do the polarity changing motion at a speed of 245 million times per second. , thereby generating vibration and tear of the bond and mutual friction and collision between the particles, promoting better contact and reaction of the active part (polar part) of the molecule, and rapidly generating a large amount of heat energy, causing the cell to rupture and causing the cell liquid to overflow. Come and diffuse into the solvent.