Shanghai Bilang ultrasonic extraction principle.
Ultrasound Extraction (UE) is a new and more mature method applied to the extraction and separation of active ingredients from Chinese herbal medicines in recent years.
Ultrasound refers to an electromagnetic wave with a frequency of about 20 kHz to 50 MHz. It is a mechanical wave that requires an energy carrier-medium to propagate. Ultrasonic has a positive and negative pressure alternating cycle during the transmission process. In the positive phase, the medium molecules are squeezed to increase the original density of the medium; in the negative phase, the medium molecules are sparse and discrete, and the medium density is reduced. That is to say, the ultrasonic wave does not cause polarization of the molecules in the sample, but generates acoustic wave cavitation between the solvent and the sample, resulting in the formation, growth and blasting of the bubbles in the solution, thereby dispersing and increasing the solid sample. The contact area between the sample and the extraction solvent increases the mass transfer rate of the target from the solid phase to the liquid phase. In industrial applications, the use of ultrasonic cleaning, drying, sterilization, atomization and non-destructive testing is a very mature and widely used technology.
Principle of ultrasonic extraction
The superiority of ultrasonic extraction of Chinese herbal medicines is based on the special physical properties of ultrasonic waves. Mainly through the rapid mechanical vibration wave generated by the piezoelectric transducer to reduce the force between the target extract and the sample matrix to achieve solid-liquid extraction separation.
(1) Accelerate the movement of the medium particle. When propagating in a continuous medium (such as water) of ultrasonic waves higher than the acoustic frequency of 20 KHz, according to the Huygens wave principle, the movement of the wavefront will cause the movement of the medium particle (including the particle of the important component of the medicinal material). The medium particle motion is subjected to tremendous acceleration and kinetic energy. The acceleration of the particle is calculated to be more than two thousand times the acceleration of gravity. Since the medium particle exerts ultrasonic energy on the medicinal component of the medicinal material to obtain great acceleration and kinetic energy, it quickly escapes the medicinal substrate and is freed from the water.
(2) Cavitation. Ultrasonic waves propagate in liquid media to produce a special "cavitation effect". The "cavitation effect" continuously generates numerous micro-cavities with internal pressures reaching thousands of atmospheres and continuously "blasting" to produce microscopic strong shock waves acting on Chinese herbal medicines. In which the constituents of the medicinal materials are "bombardded", and the substrate of the medicinal material is continuously eroded, and the medicinal ingredients not belonging to the plant structure are continuously separated. Accelerate the extraction of the active ingredients of plants.
(3) Ultrasonic vibration homogenization (Sonication) makes the effects of the points in the sample medium consistent, making the whole sample more uniform.
In summary, the medicinal substances in Chinese medicinal materials not only obtain their own huge acceleration and kinetic energy as a medium particle under the action of the ultrasonic field, but also obtain a strong external force impact through the “cavitation effectâ€, so they can be efficiently separated and fully separated. .
Characteristics of ultrasonic extraction (characteristic)
It is suitable for the extraction of the active ingredients of Chinese herbal medicines. It is a new method and a new process for the traditional Chinese medicine pharmaceutical to completely change the traditional boiled alcohol precipitation method. Compared with the boiled and alcohol precipitation process, ultrasonic extraction has the following outstanding features:
(1) No high temperature is required. Ultrasonic enhanced extraction at 40 ° C -50 ° C water temperature F, no boiling high temperature, does not destroy some of the Chinese herbal medicines with thermal instability, easy hydrolysis or oxidation characteristics of medicinal ingredients. Ultrasound can promote the breakage of plant cells and improve the efficacy of traditional Chinese medicine.
(2) Atmospheric pressure extraction, good safety, easy operation and convenient maintenance.
(3) High extraction efficiency. Ultrasonic enhanced extraction can obtain the best extraction rate in 20-40 minutes, and the extraction time is only one third or less of boiling and alcohol precipitation. The extraction is sufficient, and the extraction amount is more than twice that of the conventional method. According to statistics, the ultrasonic efficiency is very high at 65 to 70 。. At 250 °C, the active ingredients of Chinese herbal plants were not substantially destroyed. After the addition of ultrasound (at 65 degrees), the plant active ingredient extraction time is about 40 minutes. While cooking, cooking
It usually takes two to three hours, which is more than three times the time of ultrasonic extraction. Each pot can be extracted 3 times, and basically more than 90% of the active ingredients can be extracted.
(4) It has broad spectrum. Wide applicability, most of the ingredients of Chinese herbal medicines can be ultrasonically extracted.
(5) Ultrasonic extraction has little to do with the properties of the solvent and the target extract (such as polarity). Therefore, there are many types of extraction solvents to choose from and a wide range of target extracts.
(6) Reduce energy consumption. Since ultrasonic extraction does not require heating or heating at a low temperature and a short extraction time, energy consumption is greatly reduced.
(7) The raw material of the medicinal material is processed in a large amount, which is multiplied or multiplied, and has less impurities, and the active ingredient is easily separated and purified.
(8) The extraction process has low cost and significant comprehensive economic benefits;
(9) Ultrasonic has a certain bactericidal effect to ensure that the extract is not easily deteriorated.
At present, the ultrasonic extractor widely used in laboratories transmits ultrasonic waves generated by an ultrasonic transducer through a medium (usually water) and acts on the sample, which is an indirect mode of action, and the intensity of the sound is low. Therefore, the ultrasonic extraction efficiency is greatly reduced. In addition, the ultrasonic generators used in laboratories are usually more powerful.
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