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Rotary evaporator and essential oil extraction
A 50L Rotovap, also known as a rotovap, is a laboratory instrument used to remove solvents from a sample through evaporation. It consists of a rotating flask, a heating bath, and a vacuum system that creates a low pressure environment to facilitate evaporation.
Essential oil extraction is one of the many applications of a rotary evaporator. The process involves adding plant material, such as herbs, flowers, or citrus peels, to the rotating flask along with a solvent, such as ethanol or hexane. The mixture is heated in the bath and the solvent is evaporated under vacuum, leaving behind the concentrated essential oil.
The rotary evaporator is useful in essential oil extraction because it allows for the precise control of temperature and pressure, which can affect the quality and quantity of the extracted oil. Additionally, the rotary evaporation process is gentle and can help preserve the delicate aromatic compounds that give essential oils their characteristic fragrance and therapeutic properties.
It’s important to note that essential oil extraction using a rotary evaporator should only be done by trained professionals in a well-equipped laboratory, as the solvents used can be flammable and potentially dangerous. Proper safety precautions, including the use of protective equipment and adequate ventilation, should always be taken.
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3 Replies
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Reminds me of my attempt at extracting frangipani EO back when I was a student. My GF (and now spouse) spent our vacation on Bali and, well, there were all those beautiful frangipani trees in full flower and we loved the smell!
Whatcha gonna do when you’re in vacation and realise that you can’t use dried flowers? Go to the nearest pharmacy (pharmacist turned out to be gay… ‘t was a fun visity) and buy some pure alcohol to make an extract. Lacking any suitable equipment, proper filtration could only be done at home but by then, the brew was brown and had a nasty undertone.
The solution seemed simple: use a rotary evaporator. As quickly done as said, the brew was rotating and evaporating fairly fast. Regardless of the liquid nitrogen trap I installed, all the nice scent molecules ended up in the lab, filling the whole hallway with its lovely scent for 20 minutes, and drawing much appreciative attention by everyone passing by. What I got out of the rotavap was some quite pure alcohol and a concentrated stinky brew but no perfume.
The cuttings we took home lived for 2-3 years before falling pray to spider mites without ever setting flowers…-
Just to help you (@pharma) troubleshoot should you ever try that again, that probably means that you set the vacuum too deep or your coolant wasn’t cold enough. The organic compounds giving the scent you wanted were likely so volatile that under vacuum they didn’t recondense when exposed to the coolant in the condenser - they were still gas at a temperature approximately that of your coolant at the pressure inside your rotovap.
… unless you were using a dry ice condenser, in which case something else was the problem and I’m way off.
It’s also going to be real tough to separate the one compound you want from all the others with rotary evaporation alone. An extract from flowers is going to be packed with all kinds of organics, a lot of which will probably have some scent. It may take a more complex distillation to effectively isolate the one(s) you want. Ultimately, distillation in a rotary evaporator is still a simple distillation - it’s just faster, more efficient, safer, and easier due to operating at lower temperature and with rotation.
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You could try extracting the botanical scent directly with a short path distillation kit. Short path distillation is a technique used to separate and purify compounds based on their boiling points, making it an ideal method for extracting volatile aromatic compounds from botanical materials.
The process involves heating the botanical material in a flask and creating a vacuum environment to lower the boiling points of the desired compounds. As the mixture heats up, the volatile compounds vaporize and rise into a fractionating column. The column helps separate the different components based on their boiling points, allowing for selective extraction.
The vapor then enters a condenser, where it cools and condenses back into a liquid state. This liquid, known as the distillate, collects in a separate flask, ready to be collected and used as a concentrated botanical scent.
Short path distillation offers several advantages for botanical extraction. Firstly, it allows for the extraction of a wide range of volatile compounds, capturing the true essence of the botanical material. Additionally, the process is highly efficient, enabling the extraction of a large quantity of scent from a relatively small amount of starting material.
Furthermore, short path distillation ensures a high level of purity in the final product. By separating compounds based on their boiling points, impurities and unwanted substances can be effectively removed, resulting in a clean and potent botanical scent.
However, it’s important to note that short path distillation requires proper equipment and expertise to perform safely and effectively. It’s advisable to consult with professionals or experienced individuals in the field to ensure the best results and to adhere to safety guidelines.
In conclusion, short path distillation provides a viable method for directly extracting the botanical scent. Its ability to separate volatile compounds based on boiling points makes it a valuable tool in capturing the aromatic essence of botanical materials. By utilizing this technique, one can obtain high-quality, concentrated botanical scents for various applications in perfumery, aromatherapy, and more.
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