Essential Oil Extract

joe69cool · Fri Sep 16, 2005 5:56 am

Okay this is a essential oil issue I am having which actually has nothing to do with clandestine chemistry so I hope that's ok. I have recently (today) become a lab assistant for a project. The project is extracting the essential oils from various plants whose essential oil composition is unknown. The method employed by the project manager is this: Hydro distillation. It's basically a pot still filled with the plant material and salt water (concentration unknown, I dont even think he knows). Now I've seen the yield he gets off this contraption and it is LOW. A few drops of oil for two hours work. Now this just seems dumb to me. I guess it works, but it seems insanely innefficent. Plus, I think that heating for that long could seriously decompose some stuff in the oil which would thereby prevent good analysis. (actually it's sent to a different lab because this guy is a biologist) I'm just in chem 2 so I dont know much but solvent extraction just seems far more suited to this purpose. What comes to mind off the top of my head would be to soak the material in ethyl alcohol, filter, and then fractionally distil the alcohol solution. I've looked this stuff up on the internet and it looks like most people extract with hexane, distill then extract oil off the concrete with alcohol (then do some freezing to isolate the pure oil/absolute) But anyway, what I'm wondering is 1. whose method would work best and 2. why one can't just use the alcohol instead of the hexane in the first step of solvent extraction and cut out a step of the process? I'm waiting on a response back from my chemistry prof, but I am interested in what you all have to say about it.

biobrew · Fri Sep 16, 2005 6:06 am

What scale is this being done @? What plant materials?

Believe it or not, steam distillation (I think you said hydro...whatever that is...) is a very common way to extract essential oils. This is why bees buy oil rather than taking 10lbs of dried material to get minimal amounts of oil.

The specimens that your proffesor is working with could contain only a small amount of essential oil, so unfortunatly, that's just the way it has to be sometimes.

Using alcohols or other organic solvents will extract unwanted materials and will actually cause more harm than good in SOME cases. I'm sure your proffesor knows what he is doing, but from personal experience, they do get some cobwebs in their brain sometimes.

hope this helps.....BB

biobrew · Fri Sep 16, 2005 6:08 am

PS....If SWIBBy remebers right.....doesn't hexanes also pull pigments?

joe69cool · Fri Sep 16, 2005 6:15 am

Large scale. Bags and bags of stuff.

joe69cool · Fri Sep 16, 2005 9:40 pm

If anyone is curious I learned that the use of solvents can be determental because it can add impurities and might react with the oil. So I learn something every day.

nightshade · Fri Sep 16, 2005 10:38 pm

can marijuana be steam dastilled to extract the oil?

biobrew · Sat Sep 17, 2005 4:55 am

yes, but SWIBBy doesn't think SWIN will get what SWIN wants. It'll smelll and taste like the real deal, but NO THC! The butane method is golden after SWIBBy tried it a couple of weeks ago...shit can really creep up on you.

loki · guinea pig

no, cannabis cannot be steam distilled afaik, biobrew's experience would seem to suggest this is the case as the flavour oils are all known to distill (limonene, pinene etc)

extracting with alcohol or hexane and then steam distilling the residue from evapping this extract would probably allieviate the scale issues.

joe69cool · Sat Sep 17, 2005 7:57 am

Well, I did several hours of reading today on the topic of essential oils today and this is what I learned. Basically if you steam distill to remove an oil, it is called an essential oil, whereas if you extract with hexane (or other hydrocarbons) distill off the solvent, then extract the resulting concrete with alcohol, the oil is called an absolute. Solvent extraction is generally used when trying to isolate oils with delicate sesquiterpenes (Does anyone else out there have a favorite sesquiterpene? Smile

). "Steam distillation is a relatively 'hard' extraction method and will often result in a modification of the original constituents by heat induced reactions" (Volatile Oil Crops, p.57) So technically I was wrong because my process would yield and absolute not an essential oil, but my process would keep the natural oils in their more nature state. But I just still fail to see the point of using the hexane in the first place because it pulls pigments and fats and wax out of the plant material. I know the remenants of the concrete are used in the industry, but if it's only the oil you're after I think the hexane step could be skipped completely. I am going to start doing experiments on this soon, if I can get some equipment and find a suitable plant material..dandelions perhaps..Juniper virginiana leaves would be interesting, but I'm not sure if its legal. I cannot yet prove but I remain confident that solvent extraction yields more/better oil and is much faster than steam distillation. But anyway I have another question - can tiny amounts of alcohol be removed from an oil by means of a drying agent, like drying agents can be used to remove water from solutions?

loki · guinea pig

if the alcohol was methanol i'd say it could just be evacuated with 65 degrees heat. so long as the rest of it can handle that temperature that would be perfectly fine. just leaving it to sit for a day or two would probably have the same effect without risk of heat damage.

i'd say if you want to isolate stuff then some kind of chromatographic method would be needed.

bio · Working Bee

.........But I just still fail to see the point of using the hexane in the first place because it pulls pigments and fats and wax out of the plant material............

Hexanes or low boiling petroleum ether (pentane/hexanes) is preferred as it will dissolve a far greater quantity of oils than alcohols without dissolving water soluble
substances.

Pigments etc are dissolved far less than with alcohols. This can be minimized by drying the material before extraction, using low temperatures (ambient) and the shortest possible time. Multiple fast extractions are preferable to one long extraction
to minimize waxes etc which can be washed out (crystalized) using water.