Few weeks ago during lab classes at natural substances me and my friend from a working pair got a task to obtain lavender essential oil from dried lavender flowers. I was pretty excited about this and I though it would be a great opportunity to take some pictures and show you some stuff. Into the lab we went, prepared everything necessary for this lab excercise and started our work to do our best!
We weighed 15 grams of dried lavender flowers and put them into the round-bottom flask shown in the picture. After that we measured 100 mls of water and poured it into the flask. In the meantime my friend ‘built’ a set to perform water vapor distillation process. In laboratory conditions this process is the best and most ‘efficient’ way to obtain essential oils from any dried vegetal material. When our set was ready to start we had to wait for the water to start boiling. I’ll tell you more about the process.
Water vapor distillation process is a process to extract essential oils from natural substances like flowers, needles, peel. How does it work? The heart of a set is a kettle with boiling water. Once water starts to boil you can start the process. You connect the kettle with a special distillation joint which is put into the flask with water and your material, lavender in this case.
Water vapor starts to create bubbles in the water and it warms up the content of the flask. The hotter it gets the more intensive the process. Inside the flask water vapor slowly saturates with fragrant, volatile compounds from a substance you’re distilling. This is the condition a compounds needs to meet for this process to be effective – it has to be volatile in temperature of 100*C, boiling water. In other case it’s not gonna work. Sorry.
fragrant compound saturated vapor flows up inside the flask and it goes into the “knee-like” part of the water distillation joint. Here the vapor cools down, water cooler (that slope glass pipe) helps the vapor to condense into drops of water. Once a drop is big and heavy enough it slides down the slope inside a water cooler and lands in the Erlenmayer flask, a receptacle. At this point what you get is a scented water, not an essence yet. Water vapor distillation process requires a lot of patience. It takes few hours to collect 250 mls of water distillate. Then you can make another steps.
Now that you have a water distillate of your favourite flower, citrus fruit or spice it is time to perform some extraction. What’s the deal? All fragrant compounds are organic chemicals which dissolve better in organic solvents. So I put that 250 mls of lavender water into a separator and added 50 mls of methylene chloride. Organic and inorganic don’t mix, they make two phases (like water and oil). You shake the set for a while, wait for these two phases to separate completely and then you pour out the organic phase into the beaker. You repeat this process several times (we had to collect 300 mls of methylene chloride lavender extract) We’re almost there!
The last step is to evaporate as much of organic solvent as possible. Rotary evaporator comes in handy here. You just connect a round-bottom flask with it and wait for the solvent to slowly evaporate. When the entire solvent ‘flies away’ you get what you wanted – the essential oil of lavender (or something else). It’s amount is very… ehm… big. From 15 grams of lavender flowers we got a whopping 0,178 gram of essential oil – that’s 1,19% of efficiency. And that’s A LOT! Plants etc contain essential oils in a very small amount, from just a part of a per-cent to 2 or 3 percent, usually not more. Now you can imagine how much lavender I would have to use to obtain just 10 grams. This explains why natural essential oils are so expensive.
Few olfactory words. When I smelled the essential oil I obtained during that lab classes it wasn’t really great. The smell was quite rough, a little bit harsh green and herbal with the tiniest smell of lavender flowers. It didn’t remind me of lavender I smell in perfume. Still I’m happy I made it! It was fun to do something that closely connects with my passion. Hope you enjoyed the post.
[note: all pictures are my own]