Residual Solvents in CO2 Terpene Fractions

Hash and Stuff Extraction
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Hey all!

I’ve been doing R&D on terpene pulls using a 20L IES machine. The terpenes come out relatively well with minimal (if any) waxes and fats pulled along with them, mainly just some water to be separated out. The smells are there and we’re looking to reintroduce the terps into cartridges to launch a new product line eventually, but we’re hitting a snag with residual solvents being found in the terpenes when sent out for testing. We’ve had Ethanol, Methanol, Acetone, and Iso spikes and although we use Ethanol, Acetone, and Iso in our facility, only Ethanol is used in our actual CO2 lab for cleaning, and there’s absolutely no Methanol in the building.

I’m curious if anyone has ran into this issue, and if so how they were able to remediate it?

We do Bi-weekly cleaning runs on the IES using Ethanol in the solvent chambers to help out but have since then stopped recovering the CO2 used during these runs to prevent any ethanol from contaminating our old tanks and have also purchased an entirely new tank to be used specifically for terpene pulls and still have ran into this problem.

Any wisdom that could be offered would be very appreciated!

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Did you get consistent results from different labs ?
And what levels do they see in your extracts samples ?

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have a conversation with your testing lab. Causes could run the gamut from bad standards to poor sample prep on their end to, of course, inadvertent cross contamination on your end.

There is no way to pop for solvents not present in your facility. I think acetone can come from a degradation of terpenes during electrospray (IIRC?)

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Never got consistent results from different labs, it’s actually been all over the place, one lab even passed some that popped hot at other labs. Been a frustrating experience all around, but after reintroducing them to distillate it’s dropped the ppm to passable levels on the ethanol. All other solvents register at passable levels to start with, they’re just in there somehow. We’ll have to send in an unwinterized slurry to see if it pops hot for anything, not something I had actually thought of so thank you! Anything that gets sent for residuals has usually already been through the winterization process and has the majority of the ethanol removed so it’s not something that we’ve had to deal with from CO2.

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what are the relative MeOH/EtOH levels?
there is some MeOH in most EtOH…just not a whole lot.

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The last batch we sent out failed with 1,142ppm EtOH

it also contained

29ppm Acetone
160ppm Isopropyl Alcohol
23ppm MeOH

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what is your ethanol source?

10% iso & 2% MeOH seems high even for the cheap stuff folks use for cleaning.

as mentioned above, you can actually achieve acetone out of cannabis.

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You shouldn’t be getting any ethanol contamination in your solvent tank, we would go as far as doing ethanol clean runs as much as every 2 to 3 runs and never ran into this. If you want to minimize trace amounts of methanol from possible sources, you could use grain alcohol (everclear) instead 99 percent etoh which has a bit of IPA (isopropyl alcohol) in it.

Like everyone is saying, my best guess is the testing lab standards that they have in place might not be so sound. What kind of parameters are you running for the terpenes? This may have an affect on the terpenes you are extracting causing unwanted formation of acetone like @cyclopath has suggested.

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Our parameters we’re running for terpenes are 1160psi x 104°F x 30-90min with our expansion temp set to 81°F.

When we spoke to IES about the problem they were the ones who brought up the idea that our tanks might be contaminated with EtOH so we actually removed the valve stems and attempted to clean the tanks out ourselves but still continued getting the same residual issues. Starting to think they suckered us into buying another tank :laughing:

And yeah testing lab standards seem to vary wildly from what I’ve seen when it comes to these terpene samples we’ve sent out.

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I agree. Sounds like the testing lab is the one with the bad practices. Years ago I had CO2 terps fail for acetone. But not often. And although the people at an individual level at IES. Are great. As an organization just like every CO2 machine manufacture I’ve ever experienced. They all over promise and under deliver

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Could be from cleaning. I think iso breaks down into acetone.

Use limonene to clean.

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@ShogunOni Be aware what we have been calling terpenes is a chemical soup of thousands of individual compounds per strain/batch/run. Many of these compounds are well characterized, many if not most (by # not concentration) are not well known or characterized. When you make chemical soup as a process it is difficult if not near impossible to predict what kind of chemical reactions can take place during processing, storage, and consumption. Take into consideration that, yes bad cleaning can play a part in failed RSA tests, and additionally depending on the grade of solvent you buy it will not be 100% that solvent and will often have really really weird stuff in it at trace levels. Like if you buy d-limonene to avoid as an example IPA/ISO, you literally have no idea if your commercial d-limonene is also contaminated with solvent, AND you have no idea what other terpenes are at trace levels in your “d-limonene” used for cleaning.

With this information in mind, be aware that many of the known and well characterized compounds in “terpenes” readily convert/degrade/evolve into ethanol, methanol, IPA, hexane, toluene, especially acetone. And benzene under certain conditions. There are some terpenes specifically that are more prone to this than others and certain terpenes degrade into certain solvents. Also some of these compounds degrade into molecules that can be mistaken for solvents, but are not solvents at all (at least on the test). In addition to that, terpenes have pre-existing non-solvent molecules with virtually identical retention compounding the issue of the actual testing because they can be confused for solvents. Now this solvent generation can occur readily at all stages of the entire process cycle, from cultivation, extraction, storage, shipping, and especially the analysis itself (hence different labs saying different things).

It’s like everyone here all keeps saying I think instinctively: “Terps hate heat, light, and oxygen”, and I’d like to amend that statement by saying “Terps hate time”. Terps still turn into “solvent” (much more slowly), even if stored in totally inert containers, cryofrozen, and oxygen free. When exposed to ambient air and even ambient workplace temperatures the terps degrade in real time, it’s not a trace reaction.

Now one might ask: What happens when I use the vape though?..

TLDR: There are many factors at play with this issue.

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Just WOW! Thank you so much man, you point out some very interesting things! I’ve been looking into the quality of our ethanol and found it was definitely lower quality I was using, since changing that and also beginning to store terps in capped amber glass bottles in the fridge I think we’re definitely moving in the right direction. The last 2 batches of terps that I sent in for testing even passed for residuals with nothing detected. You’re a gentleman and a scholar sir!

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It really is amazing how little some people care about the unknown portions of terpene profiles. Not anyone from this forum, but people leading companies and making decisions about products with little/no lab/chemistry experience. You point out something seemingly obvious, that is often interpreted differently, the idea of preserving terpenes.

Yes we want to “preserve” the whole terpene profile, often by extracting live and carefully post-processing, but that is more of fully extracting rather than preserving. Assuming you dont blow all your volatile terps out the back of your vac oven, preserving to me seems to be about maintaining the same profile, or limiting reactions happening inside the product. We talk a lot about degradation and avoiding it, but that is only one avenue to explore.

I always wonder about how terpene profiles change overtime, when you aren’t losing any terps to evaporation. They definitely change, you can tell just by smelling. Are any of these changes “good”? are any of them “bad”?

Good meaning maybe a new compound is formed by a reaction between components in your terp mixture that change the effects or taste for the better.
Bad being the formation of compounds that are harmful, or at the least off putting.

Very interesting stuff to think about, but a bit over my head to investigate. Now I’m just rambling.

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we really should be calling it a terpenoid fraction, or even possibly the entourage fraction in reflection of the unknowns present.

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Can you explain why limonene is good to clean? Noob here

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I have had tests come back positive for acetone when I cleaned with iso alcohol

I accidentally won a secret cup high terpene award when I cleaned with limonene.

I wasn’t properly pulling a vac and heating the cls with either cleaning agent but I’d rather have botanical terps than acetone on my coa

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@ShogunOni

I’m going to spill the beans (partially) because I’m bored and I figure your thread is the most relevant (that I’m aware of).

You’ll likely see if not have already seen perceived or actual “waves” of solvent go through your lab(s). While this again can come from numerous sources and often the sources are cumulative (combined). The solvent “wave” can be extended especially in CO2 systems that recycle the CO2 because the solvent accumulates if it’s not brought out of suspension.

So, processing is going according to plan, things are great, then bam, bad testing, customers complain, Chads start freaking out and laying blame on both the labs and the techs, re-testing occurs (Possibly even at different labs) and remediation plans are made, testing labs double down on their claims that there’s solvent in the terps, and everyone is like how is this even possible we don’t even have “x” in the building.

Cannabis raw material varies on terpene content depending on the genetics. While there is a chemical soup effect, the primary compound is usually a monoterpene and ranges between 10-35% by weight (in the pure terp fraction), flower is usually around 1% total terp content. The primary terpene will either be alpha-pinene, beta-myrcene, d-limonene, trans-beta-ocimene, or terpinolene. Now it’s not going to be a single terp per strain, sometimes near 50:50 splits exist and there are strains where all 5 are near equal concentrations too, but most have a single dominant compound and then trace compounds ranging from 10-0.01% (and less) by weight.

I am not including sesquiterpenes because that is a whole completely different issue, but imo they should be removed completely from the product for numerous reasons.

Now to the point, each dominant monoterpene has vastly different stability characteristics.

Pinene: Very Stable
Myrcene: Slightly Unstable (for solvents, not for creation of other undesired compounds)
Limonene: Very Stable
Ocimene: Extremely Unstable
Terpinolene: Extremely Unstable

Knowing this phenomenon, much of the solvent in terps can be predicted with absolute certainty. Also knowing this, you can ask your testing lab, hey how are you analyzing for solvents?, do you use a GC? Do you use a GC with headspace? Do you use a GC with MS? And finally what are the temperature settings in the instrument.

What I’m getting at, is if you run a terpinolene strain, Jack Herer for instance, you will be at odds with solvent generation the whole way through, and arguably it’s almost pointless to have it analyzed for solvent, because the testing generates solvent. Simply shipping your sample even to the lab will create solvent, and for the sake of argument you ship with cold packs, but then the testing lab will remove the sample from the cold packs, prep the sample, then it sits on the bench and in the autosampler for at least an hour optimistically and solvent again is generated.

Knowing this opens up a much deeper issue.

Should these specific terpenes be consumed at all in a heated vaporizer device?

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That’s a really good question about whether these specific terpenes should be consumed at all in a vaporizer. I personally wonder if the concentration amount of the terpene is the bigger issue when it comes down to consumption and vaping though since when you’re smoking flower you’re also smoking the terpenes correct? At flower concentrations I’m sure it isn’t that big of an issue but when you’re mixing in high concentrations after extraction with distillate or oil it definitely makes you wonder how good it is to be smoking what is essentially a solvent lol

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For sure. The higher the initial concentration of the reactant, the more solvent you get.

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