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.
1 Like
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.
1 Like
It is rather silyl groups which are employed to derivatize cannabinoids. Ethyl acetate can serve as a solvent/catalyst for such reactions.
3 Likes
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) "
1 Like
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?
2 Likes
Yes boss.
Already know I can turn almost anything into a smoke machine…
https://www.amazon.com/Every-Machine-Smoke-Operate-Enough/dp/B07JFQKNYN
3 Likes
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
2 Likes
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!
3 Likes
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.
4 Likes
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.
1 Like
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. 
2 Likes
If anyone is curious this is a really good analysis http://volcanovaporizeruk.co.uk/pdf/cannabis_vaporizer_combines_effective_delivery_of_thc.pdf
2 Likes