I occasionally get small amounts of THCA in my distillate… so it can vaporize without decarbing… but it’s always less than 1%.
I think I probably still need more context. There are methods to do this kind of work. Without using a GC (which is too hot…) but all of those methods still require vaporization or some other kind of combustion to get the stuff to become a vapor to be trapped as a gas. You know? So you are losing a portion.
Why are we concerned with losing the portion? What am I missing here? We could start by quartering and establish how much of an ACID there was in mols. Then we could use the GC and establish how much of each kind of substance is present (without switching away from established science) and then we could back calculate the total amount that would have been acidic to begin with.
The level of calculations needed… I mean its a lot.
I’m not sure about the other hypothesis that are given in the links because of these two items.
- Vapor/Combustion does not necessarily happen at the same rate of change and energy exchange as decarb
- You could potentially control decarb rate and therefore allow it to be carried away by other vapors (not necessarily vaporized itself…but many things are just carried along) and you might do this by modulating the pH during sample prep OR by placing it on a solid state resin during sample prep.
In either case - I’m still not sure why people are interested in the amount of THCa that might be available as a vapor.
And are we just trying to do this in a lab setting - or are we trying to do this like for science and then wanting to make a manufacturing process out of it?
I suppose that’s possible. My autism often gets in the way of understanding things that are sarcastic. Originally I thought the request was sarcastic… but then you posted about it MORE. 
And so I figured there was actually a reason that people were inquiring. And since I love these adventures, I figured I’d ask more questions about the why - and then propose some possibilities for how.
I suppose my real question is - do we actually need it to be a vapor (i.e. a gas in its gas for on the critical pathway) or do we just need it to be an aerosol (i.e. probably not a gas, but certainly able to be inhaled…) Cause those are different things. And I cannot tell what people are actually asking for.
In any case - collecting on a membrane should tell you how things are going (if you had a process for vaporizing or combusting you wanted to use). And you could also do instant IR collecting, cause you can just dab a little on the wafer and check it over and over again…depending on the wafer you could even start at X and then heat the damn thing and just keep running the same wafer over and over again.
There was a study… that indicated that an inhale of COMBUSTED cannabis included more than just THC… ah yes, this one: Chemical and physical variations of cannabis smoke from a variety of cannabis samples in New Zealand - PMC
In this study it shows that there is particulate that is inhaled during combustion activities (smoking) and that that particulate contains cannabinoids, including THC and terpinoids and such. They are, sadly, using the GCMS for their testing! However, they also use a non-GC method, but they don’t quantify the cannabinoids, because they are actually interested in terpenoids.
Looks like someone else also posted a study on vaporizer efficiency, which indicates a similar path - which is that particulate matter is inhaled at the same time, that matter may not have been fully decarbed yet.
Honestly - that makes the fact that you only absorb like 30-50% of what you are smoking make a bit more sense… because its not actually THC yet, so its not going through the same pathway that the tests are looking for.
But still - please help me understand why inquiring minds need to know. <3
You the best!
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This is where it started for me lol. My interest in pursuing the topic stemmed from my curiosity of decarboxylation temperatures of acidic cannabinoids being roughly on average 15 - 90 degrees C lower than the neutral cannabinoids boiling points. For example THCa decarbs at about 120 C and THC vaporizes at about 155 C. Any data on boiling points for acidic cannabinoids coincides with their approximate decarboxylation temperatures. So… can acidic cannabinoids vaporize without decarboxylating
@cyclopath suggested we look for any literature that looked into quantitating acidic cannabinoids in vapor (some were on aerosols), which brought a lot of interesting studies and IP.
Damn, I keep forgetting that one is chemical and other is physical, like comparing apples with oranges
In addition to the lovely selection of peer review articles, our fellow peers have been talking shop on a way to capture a THCa peak, from a vapor sample, on a chromatogram. This would suggest that acidic cannabinoids can vaporize without decarboxylating.
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Why not use a short path as experiment? As I said, I see THCA in my wiped film distillate. So just add some THCA to crude, quantify THCA in starting material. Run that through your wiped film and quantify THCA in your distillate. That should give you an estimate of the percentage of THCA that survives vaporization intact.
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That would not answer the cart question. Or the “did it splash?”
So you’d need to add a protecting group (I think ethyl acetate?) to your THCA, then mix with disty and do the GC inline analysis.
Something to consider when referencing studies performed with dry herb vaporizers is the variation that results from different devices used.
The study referenced above tested 4 different vaporizers that all heat flower relatively slowly, which results in different components in the aerosol than when flower is heated rapidly.
Sep Funnel Gravity bong. Cool and agitate with leftover solvent. That was my idea.
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It is rather silyl groups which are employed to derivatize cannabinoids. Ethyl acetate can serve as a solvent/catalyst for such reactions.
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I tried hyperlinking to an agilent SOP, but it didn’t work.
and you are right about the reagent… I didn’t read to the second page
" N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) with 1% trimethylsilyl chloride (TCMS) "
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To clarify the question at hand is:
“What does the cannabinoid profile look like after combustion/vaporization at a certain temperature?”
And subsequently how to carry out the combustion and test for the profile (possibly with LC).
Is that a correct understanding/summary?
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Yes boss.
Already know I can turn almost anything into a smoke machine…
https://www.amazon.com/Every-Machine-Smoke-Operate-Enough/dp/B07JFQKNYN
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As some have suggested, GC will not work for this. Either you run it straight and get vapor, which maybe you could have you inlet and oven at the desired temperature, but the retention time means an unrealistic exposure time to the heat. If you derivatize, you will get a stable profile in vapor, but the wrong profile.
So as you said, LC is the only way I can think of, which is very strange, but somehow right.
Combustion/vaporization needs to be done with the exact device the concentrate is going to be used in, as the resulting data will be mostly dependent on how the device heats, and of course the concentrate used.
@Cassin has given a couple good ways to go about this, the easiest being:
vapor to bubbler to dilute n shoot to math
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That’s why I been looking at the total signal of vapor without chromatography.
This is quite a complex endeavor.
One can make a parallel with analyzing cigarette smoke.
The intro of this paper sum up the main approaches.
There are various levels of analysis to be done: gases, volatile, particles, stuff sorbed on the particles… I guess you are mostly interested in the volatile fraction. GC would be more convenient than HPLC, for volatiles, especially dealing with terpenes, and also for gases and aslso other organics like acetone…
I think its kind of great that today in the ASTM D37.08 call that the broader standards group talked about this specific issue. The standard has already been started and there’s a real focus on how this will work coming out of Colorado (they dedicated some gov’t funding to it).
Always nice to know that our thoughts are being mimicked around the world. Front and center adventures FTW!
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Also check out this paper on the subject of testing for heavy metals and methods - different, but similar methods discussed for collecting the vapor and what not for downstream testing… which is what we are talking about.
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Might have my math wrong
but this gave me the idea that if one was not to exceed 65 C (or 150 F), the approximate decarboxylation temperature for THCa, we could vaporize the compound by lowering the boiling point by decrease the atmospheric pressure.
This along with a few online Boiling Point Calculator
Theoretically, THC could vaporize below 65 C (150 F) at a pressure below 136 torr. If the physical properties of THCa have any resemblance or similarity to THC, one might observe the vaporization of THCa without decarboxylation occurring. And if this could occur, it would be interesting to see if the phase change(s) between solid and gaseous THCa are multi step (solid to liquid to gas) or straight sublimation.
Now after rechecking the math and reminiscing all of my distillation runs, I’m finding it hard to believe this would work. Under a full vac, I cannot recall seeing any significant vaporization occurring with the exception of solvents and volatiles.
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That is by Dr. Thomas…and he’s really against all heavy metals getting into our bodies. Which I think is kind of great. I think he clears out some issues with how to collect things safely. Some of the issues are not as important for seeing cannabinoid differences before and after, the apparatus and some of the references a bit helpful.
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If anyone is curious this is a really good analysis http://volcanovaporizeruk.co.uk/pdf/cannabis_vaporizer_combines_effective_delivery_of_thc.pdf
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