Im a new member, and a pretty basic chemist at best(biologist by profession). I’ve been using a dry-ice iso setup at various temps under the assumption it will carry less chlorophyll in the process(originally I was doing quick iso and only recently switched to dry ice), and would very much like to also hear if ethanol is superior to iso at very cold temps, and also whether I should switch to 95 rather than abs.
Also one last question, I have been concerned about adding dry ice directly to the solvent, as it tends to dissolve and change polarity/pH. Is that an issue, or does it not really matter?
are you recovering your solvent?
I made the switch to Ethanol from Isopropanol slightly before I had solvent recovery established. It was a huge relief not to have to deal with the stench of boiling Iso. Solvent recovery followed very quickly, to ameliorate the 5x jump in solvent cost per gallon. So win then win 
If you’re using 200proof, and recovering it, you’ll need a way get from 190 back to 200. Or not, because scuttle-butt around here says 190 works as well or better.
As a Biologist, you might appreciate my logic on the safety of Ethanol…
We’ve been dealing with ethanol in our diets for some 2million years, since we came down from the trees and started getting our fruit off the floor. we’ve been selecting for tolerance to this stuff essentially forever. If your genetics don’t allow for ethanol metabolism, and mine do, whose genes get passed along? How about your mate. you’re both passed out. I’m not…
2 Likes
I don’t recover my solvent, and my process is small scale so its not an issue yet(as I dont pay for the solvent ).
I evap the iso to the point where i see co2 bubbles(ive been following skunkfarm’s instructions quite thoroughly), and then I add 50 ml of eth abs and either winterize or straighforward evaporate. Whatever little iso may have stayed in the first stage, I highly doubt it would remain after the second evap. If I’m wrong, feel free to correct me. Either way, if 95% eth is better, by golly I’d be switching like there’s no tomorrow. I was using iso so far just because I was under the assumption it will tend to pick less chlorophyll as it is less polar. Didnt really kbow that for a fact… Just made an assumption.
Do you have the specs on the 200proof you’re using. they are not all created equal. Used to be all 200 proof was made using nasty drying agents you do not want to add to peoples meds. Now you can find many sources using molecular sieves to pull that last 5%, and those are generally considered safe.
The only claims I’ve seen that Iso was a better solvent with our favourite biomass came from someone who I believe was using 151 rather than 190. although I could not get them to confirm.
As far as Iso removal, I don’t know that you’re achieving a whole lot with your 50ml of ethanol. your second solvent has a lower boiling point than your first, so is not likely to help remove the Iso as much as say adding a little water and boiling that off.
How are you evaping off your solvent. a rice cooker from the thrift-store works well if run outside with good ventilation. they are designed to stop cooking auto-magically when they go above the boiling point of water. which can be helpful if your operator is easily distracted
3 Likes
I do have the specs. This is lab grade but I’ll go over the specs - anything I should be specifically aware of? I did a preliminary residue check by boiling off 200ml but didnt spot anything.
I’m evaporating in a very primitive double boiler setup consisting of a beaker placed into water kept at 80-90c more or less. Yeah I know it’s street but I’m learning, and so far did not commit a budget.
lab grade? would that be reagent? analytical? HPLC? Specifically sold for extracting Cannabis (it exists)?
yes. you need to be aware that “lab grade” has most likely been dried with nasty chemicals. You need to source some that has been dried with molecular sieves. Or just go with food grade 190.
Evap and look for residue? you won’t spot the benzene that way.
you will likely have to ask the manufacturer how they got there.
Like I said, I’m not a chemist so I’m learning. I’ll check the bottle tomorrow and get back to you on that. I imagine you might be right though. Is a lesser prcentage one(which if memory serves me right, is either 95 or 96%) be a safer alternative?
1 Like
In many states you can find 95% (190 proof) Ethanol for sale in the liquor store. That is were I suggest you start. 200 proof does not seem to offer significant advantages over 190 for cannabinoid or terpene extraction.
200 proof carries the possibility of having been dried using chemicals you don’t want in your extracts…and it’s often non-trivial to figure that part out.
The 100% non-denatured, molecular biology grade ethanol sigma sells is probably made without benzene. The certificate of analysis claims less than 1ppm Benzene. Without that information, I’d just be guessing. As it stands, it’s still only an informed guess.
If you can’t get 190 from the liquor store in your neck of the woods, try Amazon. Avoid 200proof unless you can verify how it was dried.
1 Like
Thank you very much for the detailed explanations. Sent you a message as well.
I guess I could go look for myself**, but I’ve heard rumour that CA requires food grade solvent for extraction.
Doesn’t that take heptane denatured Ethanol off the table?
edit:
§40223. Ethanol Extractions
(a) Ethanol used for extractions or for post-extraction processing shall be food-grade
**I’m in OR, it’s not really my problem…
This has always been an idea of mine. But have always been somewhat skeptical. I’ve always considered that if u had a saturated solution and you drastically reduced its solubility, you would obviously crash out what ever was in solution. But all the variables have made me somewhat skeptical. Do u have any experience using this process? And would there be something better than water to use in order to reduce the etoh solubility? As well I would assume that your sample would have to be as clean as possible, ie. Remove lipids etc. But then where does that leave all the terpenes? And what role would they play on the solubility.
Also I recall reading one of @Photon_noir comments on how alcohol breaks down the DNA chains of plants (I can’t quite remember the entire conversation but can certainly recall the destructive nature of alcohols and DNA and was curious what role that would have on the entire process as well)
I dont know the context but alcohol doesn’t destroy DNA.
1 Like
Indeed, it is commonly used as a component of a dna buffer soultion.
solution.https://www.google.com/amp/s/www.researchgate.net/post/Does_anyone_know_what_the_effects_of_denatured_alcohol_on_DNA_preservation_are/amp
This is dispensary grade extract testing nominal at 65% THC. I placed it into rubbing alcohol at 70% iso and 30% water. The white clouds roll out of solution within minutes really but this was left at room temp overnight.
The white clumping strands are very long and seem to twist out of solution using rubbing alcohol. The white chunks that form tend to form a layer on the bottom of the vessel and are like wax. If the white cloudy strands represent DNA then it makes sense that I see so much of it precipitate when I dewax like I do using rubbing alcohol versus ethanol.
The idea is to get a solvent just barely strong enough to keep cannabinoid in solution but encourage all other compounds to drop out of solution. Isopropyl alcohol is crappy at holding onto DNA and like compounds compared to ethanol. Add water and it really rejects those solids. I always keep coming back to iso for a whole range of steps. It is cheap but it is much more versatile than I generally see blog posts about. There are some very cool nuances with the stuff in labs but here is a link that talks a bit more on topic about just why you might select one over the other.
4 Likes
I am almost positive I never said anything about alcohol breaking down DNA. UV light can damage DNA… but DNA has little to nothing to do with extraction in this case, anyway… which is another reason I am sure I never said that.
Is there someone else on here or another forum going by my nickname? I am getting misquoted and just completely incorrectly remembered or interpreted a lot, lately!
Water over 5% in ethanol (more than the azeotrope, iow) causes resin to begin louching (milky microemulsion), or crashing out of solution, as you say. This can be extracted by partitioning with a non-polar solvent.
My apologies @Photon_noir I was absolutely wrong about what I said about alcohol damaging DNA. Because I was unsure myself I decided to try and find out where I got that idea from in the first place, and then only common ground between my “not so good memory” and Google (lol) was the fact that ETOH and IPA both caused the DNA and RNA to precipitate out, which would obviously cause some problems during a crystalization step for the record 
lol my appologies! Hopefully detention isnt too long I have plans today lol
No worries. I’ve just been getting that a lot, lately. I guess it’s a hazard of being everyone’s chemical encyclopedia. 
4 Likes
I just wanted to repost this chart with my highlights and labeling the x-axis for those who missed it. It shows the relative alcohols’ (isopropyl and ethanol) and their water azeotropes’ (iso~86%, EtOH~95%) solubilities of vegetable oil, which is mostly composed of fatty acids, triglycerides, and some phosphatides (aka: lecithin and friends). This plot answers a lot of the questions asked in this thread.
3 Likes