subcritical terpene extraction opinions

Recently did a terpene run on some dried lavender at 1180psi and 42c (supercritical) and failed our RSA test for acetone. It’s strange because we don’t have any acetone in the building. So I’m thinking that we converted something with in the plant to acetone do to the amount of pressure and heat of a supercritical run. I would like to know if anyone has had this problem them selves? Is it possible to pull terpenes in a subcritical state? Do you find subcritical to be more beneficial for the terpenes? What parameters are you finding that give you the best results?


Or breaks down to Acetone in the mass spec?

I’m a little fuzzy on how IDs are made on the mass spec, but I know it involves breaking the molecules into pieces and flinging them into a vacuum. Confirming the ID in another manner would be ideal. They may also have GC retention time in addition to ion mass & fragment masses. In which case it’s probably harder to argue mistaken ID.

Chances are PhD level analytical chemist is required. @drPaul?

I like to refer to 3rd party testing as “ask a stranger”, but the truth is you should already have made friends of the head chemist at your 3rd party lab.

Do so, and then ask them for help figuring this out…

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No doubt I’m working on that currently. The guy is damn near impossible to get ahold of unfortunately. @drPaul If you have any info it would be greatly appreciated.

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From my understanding even cannabis can produce acetone in trace quantities. Given that plants bio-synthesize many types of ketones, it would make sense that there may be traces of the most basic ketone, acetone. @Photon_noir could probably speak more in depth to this. Perhaps the polarity of your CO2 at those conditions concentrated some acetone, or broke down other ketones present. I have also had RSA’s test for acetone in hydrocarbon extracts, when there has never been any in the lab. Never failed for acetone, but there was definitely a spike.


I am not an expert on lavender, and I cannot speak to any more useful depth on the subject, since what you said is likely the right answer.


Were you able to determine the cause? Are you sure it wasn’t a lab error?

As for as I can tell it was not a lab error. We have been crazy busy and haven’t had a chance to try it again but we need to. Do you run CO2?

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Not yet but I’ve heard 1100 is a good pressure for terps.

34 Celsius

interesting I might have to give that a try.

To my knowledge you can pull terps in a subcritical state but its going to be more “whole plant”. You will be getting a lot more that just the normal terps and hydrosol when you run subcritical. I’ve been told , you’re going to be looking for a density of around 0.63 for a subcritcal terp run

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We just tested are HTE & lots of acetone popped up… any idea why? We don’t use acetone in our facility

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Just had the same experience here at 1050 PSI and 30C on the extraction vessel. Great looking terpene fractions, but tons of acetone. We have never had acetone anywhere near our SFE so I surmise it is being produced from the plant material under the extraction conditions.

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How are y’all getting the testing done? Unless it involves mass spec (or nmr) it’s possible that something else is getting mistaken for acetone

Gas Chromatography here. We also picked up some hexane which was odd. It’s worth mentioning that this is after a low temperature distillation at deep vacuum levels to pull the terpenes over. Mantle temp went as high as 40C with vacuum levels at around 100 microns.

my experience with co2 terps is they all smell the same. pretty good, but the same. more planty

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Yeah so GC works by checking the time a type of molecule takes to go through a capillary column, so if you happen to have a molecule that takes the same time to go thru as acetone, the GC just says “it’s acetone”. If you are really sure that theres no way acetone or hexane is in your sample you can send it to a analytical lab that has GC-MS and a terpene library. It cost more but if you sell your terps is worth it imho to tell your customers that it’s not poisonous

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Thank you for the insight. I may just do this. It would be nice to know for sure. Otherwise these terpene runs are just a fun parlor trick. My boss doesn’t really get off on that stuff.