Rotary evaporators are often used in experiments such as synthesis, separation, extraction, and purification. The unique rotary evaporator design greatly improves its additional efficiency. They are now widely used in pilot and small-scale experiments in laboratories. The sealing performance of the whole machine is good. Vacuuming can be done by connecting a vacuum pump to make the whole equipment in a negative pressure state, which can not only reduce the temperature required for material evaporation, but also effectively suppress the explosion and boiling of certain materials. Today I will share with you how to use a re-501 rotary evaporator to extract plant essential oils.
The principle of extracting plant essential oil by rotary evaporator:
Plant essential oils usually exist in the flowers, leaves, rhizomes and other parts of plants, as well as specific structures in their cells. During the extraction process, the rotary evaporator works by heating and reducing pressure. First, mix the plant material with an appropriate solvent, such as absolute ethanol, and place in a round bottom flask on a rotary evaporator. Then, turn on the vacuum pump to reduce the system pressure and create a low pressure environment. By heating the water bath or heating mantle, the solvent in the flask begins to evaporate and a steam is formed. The steam is cooled by the condenser tube and condensed into liquid in the condenser, that is, plant essential oil. Finally, the essential oils are collected in a drip bottle or a drip bottle assembly on the rotary evaporator.
The steps of extracting plant essential oil by rotary evaporator:
Prepare plant material:
Select appropriate plant materials such as flowers, leaves, rhizomes, etc., and prepare them, such as washing and chopping, to increase extraction efficiency.
Put the plant material into a round-bottomed flask of a rotary evaporator and add an appropriate solvent, usually absolute ethanol or dimethylformamide (DMF), etc.
Connect the rotary evaporator to the vacuum pump and turn on the vacuum pump to create a negative pressure environment. Start the rotary evaporator so that the solvent in the flask begins to rotate. At the same time, heat a water bath or heating mantle to provide an appropriate heating source.
Evaporation and Condensation:
As the solvent is heated and rotated, the solvent gradually evaporates and forms a vapor. The vapor is cooled by the condenser tube and condensed into liquid in the condenser. This separates the plant essential oil from the solvent.
To collect essential oils:
Collect the condensed essential oil through the drip bottle or the drip bottle assembly on the rotary evaporator. Essential oils usually form a layer on the bottom of the drip bottle.
Through the above steps, the rotary evaporator can effectively extract essential oils from plant materials. The advantage of the rotary evaporator is its ability to control temperature, vacuum and agitation speed, making the extraction process more efficient and controllable. In addition, the sealing performance of the rotary evaporator can prevent the volatilization and loss of essential oils.
It should be noted that when using a rotary evaporator for plant essential oil extraction, ensure that the operating environment is well ventilated to prevent the accumulation of harmful gases. Also, make sure to use proper safety measures and protocols based on the nature of the plant material and solvent used.
To sum up, rotary evaporators play an important role in the separation and purification of compounds such as plant essential oils. Its efficient evaporation and condensation system, as well as precise control of temperature and vacuum, make the rotary evaporator one of the indispensable tools in the laboratory and industry. By extracting plant essential oils, we can obtain natural products with specific odor and chemical composition, which have wide application and commercial value in the fields of essence, cosmetics and medicine.
Case:Maceration Extraction VS Continuous Cold Extraction
Extraction from heat-sensitive analytes requires the use of specific techniques to isolate the desired compounds without harming or destroying them. Compare the ancient maceration process with continuous cold extraction on a modern rotary evaporator. Which method will stand out?
Today, I will describe and evaluate two processes by which chemists can extract compounds without destroying or damaging them: maceration and continuous cold extraction.
Maceration has been used for centuries as a method of extracting compounds. The basic principle is to soak a solid material in a liquid to release its soluble components. The process usually involves preparing the sample by drying and grinding to increase the surface area between the sample and the liquid solvent. The sample should not be too large or the solvent will not be able to penetrate the innermost cells. Samples should also not be ground too small, as this may lead to loss of volatile active ingredients. The maceration process is usually carried out at room temperature and the extraction usually takes a long time.
Another method is to isolate the desired components of the mixture by continuous cold extraction using a rotary evaporator. A rotary evaporator uses a rotary flask under vacuum and submerged in a hot water bath. The rotation creates a thin film of the mixture, which is evaporated by the heat. Vacuum has the opposite effect of my pressure cooker. The boiling point does not increase due to an increase in pressure, but decreases due to a vacuum. This allows the solvent to evaporate at lower temperatures. Modern rotary evaporators can perform more complex applications such as continuous extraction. During continuous extraction, the evaporated solvent is condensed and collected in a separate container. The condensed solvent is then reused for the next extraction cycle. This method allows for an efficient and continuous process because the solvent can be reused many times. Low temperature prevents degradation of heat sensitive compounds.
To show the difference between the two methods, I will present the results of the extraction of curcumin, the natural bioactive compound of turmeric. Both extracted samples were prepared by drying the samples under relatively low heat (50-60 °C) for 18-24 h to protect any heat-sensitive compounds. The sample is then crushed into smaller pieces using a blender.
The first extraction is by maceration. Put 250 g of sample into a glass bottle filled with 4 L of ethanol. The maceration process takes place over 216 hours at ambient temperature, followed by filtration through a muslin cloth.
The filtrate was then concentrated using a rotary evaporator to evaporate the remaining solvent, leaving the resulting extract to be measured. The continuous cold extraction uses the same sample-to-solvent ratio, but the entire process lasts over 24 hours.
The results of this test showed that the extraction process using a rotary evaporator produced a yield of 31.4%, slightly higher than the 28.7% yield of the maceration process. However, the biggest difference is the time it takes. Rotary evaporators are able to extract more material in less time with significantly less effort. Once set up, the process is fully automated, whereas maceration requires continuous intervention to achieve comparable results.
Extraction using a rotary evaporator has several advantages over maceration. Benefits include:
Efficiency: Rotary evaporators allow for faster, continuous extractions, and solvents can be reused many times.
Purer extracts: The rotary evaporator completely separates the desired compound from the solid material, unlike maceration, where the solid material remains in the extract and requires an additional filtration step.
Temperature Control: Rotary evaporators allow precise temperature control, unlike maceration, which is affected by ambient temperature.
Scale up: It is easier to scale up the extraction process on a rotary evaporator.
Solvent recovery: Rotary evaporators can recover and reuse solvents, reducing costs and the environmental impact of the process.