Isomerization of Co2 extracted Crude

I have been hearing of people having problems with distilling Co2 extracted crude oil. Most people are experiencing a decrease in potency and a mystery peak show up on their HPLC’s. I have been told this is due to the pH of the crude being off. I’m wondering if anyone has experienced this, knows what is causing it, and if there is a simple fix for it. Thanks in advance.


folks have certainly experienced this.

and noted that acidic conditions in the boiling flask are a contributing factor.

I haven’t seen any discussion of the problem being related to the extraction solvent used to obtain the distillation feedstock, but am willing to accept that the cleanup steps required between the CO2 extractor and the boiling flask could be contributing.


The reason I point to Co2 is that it is the common denominator between all these different companies. Each has a different post extraction processing method but they all use Co2. That’s the only reason I started there.


TLC the crude and use your chromatogram mystery peak to ascertain where that spot appears on your TLC plate. Run a small scale column to seperate that compound and send it into a lab to get an nmr, ir, and mass spec. If you do not have a chemist who can read these three pieces of analytical equiptment you can prolly figure it out or send it all to me and I can give it a go!

A varying ph may cause mystery peaks, i am inclined to think it could be a degraded terpene or cannabinoid because these molecules are subject to heat degradation. Moreover, heat, pressure, varying degrees of protonated and deprotonated molecules at various pHs can cause unwanted reactions.


I hear you, and it could be the CO2, but I’d put my money on something they have in common between the extractor and the boiling flask… because it happens to folks using EtOH and Hydrocarbon feedstocks as well.

Doesn’t everybody winterize their CO2 oil before distillation?

maybe we should start with your post extractor cleanup tek.

eg are you using cbleach in your boiling flask? are you using an appropriate source for your activated carbon?


high temperature with low ph could cause your problem or better yet the acid could be reacting with the unsaturation in your production to form a carbonate or if there is water in there a hydrate or peroxide

Taken at face value experiencing a decrease in potency would, all other things being equal, indicate to me that the starting crude was much further along the degredation path from THCa to THC to CBN and what comes before or after in that chain.

Let’s take an extreme comparison.

Compound A is 100% THCa and is distilled. At least some of compound A will have progressed to THC and then to CBN during the unavoidable application of heat and exposure to atmosphere. Since each step in the chain takes time only so much of the starting compound can transition all the way to degredation past THC and some cannot.

Compound B is 100% D9 THC and is distilled. Any degredation that takes place will do so into CBN first in this scenario at least and possibly even further into “mystery peaks”. For sure though much more of Compound B would progress past THC in the breakdown chain than A because it starts at THC and takes no time to get there from the acid form. Moreover any unknown reactions that take place in sizzling hot boiling flasks are also candidates to have been helped along from this.

The question back at all of you folks is this: do current lab methods normally employed accurately determine the make up between THCa and THC as a direct observation? Is it computed? Is it possible to accurately determine so as to observe this theory? The logic leads me to believe the differences between extraction methods impact the breakdown chain of the compound by likely encouraging the THCa to THC transition more than others in some way and then logically the idea is extended to the notion that any number of breakdown processes independent of cannabinoid are also impacted by extraction type and end up in the boil and then end product.

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So we are one of those CO2 extraction labs getting mystery peaks which we suspect are d10. If acidic conditions are to blame (we are investigating this) then what might be the outcome if that distillate was scrubbed in a slightly alkali solution and redistilled? Might the d10 revert to d9 or d8, in other words something more stable? I may be way off base on this line of thinking but I’m just pondering methods to rescue these batches with mystery peaks.


unfortunately you’re unlikely to get your delta 9 back with this method. it might prevent you making more next time though.


Indeed, just wondering what methods could be employed to reverse the isomerization assuming that d10 is at least, if not more unstable than d9.

chances are delta 9 is less stable. which is why our favourite isomer keeps going away when we provide the activation energy and a route.

there are folks lurking around here who are way more qualified than I, one of them might be able to address potential remediation/reversal routes…to me it looks irreversibly wrecked.

it’s also my understanding that we don’t actually have a solid ID on the isomer yet.



Hey, I did not know this was a thing.

I have had inconsistent potency in final product distilled from supercritical CO2 crude. I don’t think it’s degradation related for a couple reasons: CBN levels are usually less than 2%, D8 levels are usually less than 2%, and the chromatograms look comparable to previous distillations I have done with different methods. There is always that one mystery peak, but it isn’t particularly elevated from normal (caveat: I haven’t done a super detailed or quantitative comparison of mystery peak across methods of extract/distill). It certainly doesn’t look like a “dirty” chromatogram.

One hypothesis is that it is fats and fatty acids that aren’t getting entirely removed during winterization. The other possibility could be extraction of other unknown plant compounds that aren’t easily removed with winterization and are really hard to fraction out via distillation.

Regarding ethanol pH: I once pH’d the winterized crude dissolved in ethanol post-filtration and got a reading of 5.6. Just checked my ~95% recycled ethanol and it’s 6.2. I am skeptical that pH is an issue for the reasons I mentioned above about degradation.

Can anyone else share a pH reading on ethanol-extracted ethanol solution, or butane crude/ethanol mix post-filtration?


I definitely agree that in some instances it’s likely fats, tryglcerides, etc. However, there are also instances where the mystery peak is there and interestingly it coincides with the data that Zack Iszard presented in his YouTube video. See this thread:

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There was this I did, it was just recycled etoh.


When you diluted with water and the pH seemed to shift, did you use tap water or distilled water?

Distilled water. I think the addition of the water shifts the pH, changes the moles in solution by dilution . But the etoh is still acidic.

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