[tacco]

hi, I'm an Italian student of pharmacy, I'm trying to extract essential oil from plants and flowers.
i thought about vapour extraction or solvent extraction, the problem is just that I'd like to have some suggests or useful links i could visit and read, because I think that my Italian's information are not so clear and I believe as more clear to understand English/American instructions, but I couldn't find them easily out of internet. I would be grate if you could give me some suggestions or keyword.

greetings to everybody.   

[vmelkon]

There is steam extraction. There are different ways, different equipement can be used.
Boil water from one flask and lead vapors into another flask and from the the vapors reach a liebeg condenser.
I have done this with a single flask : plant and water in the same flask.
There are a few videos on youtube. Personally, I like to see it in action and see how the equipment is setup.
There is a 3rd way. Some kind of flask with 2 exit ports, top and bottom. Connect this to a standard RFB. The RFB contains the water. Put the plant into the 2 exit port flask. Of course, connect a liebeg condenser to this.

By solvent extraction, perhaps you mean using a soxhlet. This is pretty simple.

[Archer]

For best results you need a Clevenger apparatus. This will collect essential oils over a long period of time. If your oils are high in sesquiterpenoids then steam distillation from one flask to another can take 4+ hours. It is best if you can just leave the Clevenger unattended for four hours while it collects the oil (provided the water to the condenser is not turned off)

Some essential oils are hydrolysed by steam distillation, for example matricine from German Chamomile is hydrolysed, decarboxylated and dehydrated to chamazulene during steam distillation.

Therefore it is sometimes prefereable to solvent extract and then purify by short path vacuum distillation to remove the non-volatile materials which have been extracted. Not ideal for small quantities. As some oils are 0.05% of the fresh herb this can be a lot of plant for very little oil.