Decarboxylation Efficiency

#1

Hi all,

I’m wondering if any of you with in-house analytics have done studies to optimize decarboxylation efficiencies. What are you typically seeing for these values?

Theoretically at 100% efficiency, 1 kg of dry, non-decarb’d extract that is 100% THCA by mass would yield you 880g of 100% THC after accounting for mass lost during decarb.

Anybody have an efficiency value that they’re getting that they would not mind sharing? Ours are 70-75% which seems low and I’d love to compare.

Thank you all.

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#2

Hmmm ok what methohod of decarcoxilating are you using
Crude is never 100 % thca
And a lot of volitales and left ssolvent make up for the 1 kg of crude wich if well winterized is less than one liter
Second who calculates your numbers by wich machine and wich comparisons

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#3

Hot plate heating. My example was only theoretical of course. I know there are volatiles/solvent leftover.
We use HPLC for analytical testing. I am saying we have a potency after rotovap/before decarb, and also have potency post-decarb. By mole ratio, what is the max efficiency? Considering there are side reactions when heating to 140C.

#4

The theoretical conversion of THCA into d9THC is .877, but the real conversion rate is .68 because the reaction does not occur perfectly. So 100 grams of THCA converts to 68 grams of d9THC in the real world.
Hugh Goldsmith
SRI Instruments
We make the equipment to measure the THCA and d9THC

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Its all about the Delta 9
#5

Thank you Hugh for your actual results!

#6

What does the rest of the thca turn into? can you seperate it from the thc?

#7

@Krative @wc15 @Dabatronicus,

What do you guys think about this statement?

Does THCA really turn into other things besides delta 9 when decarboxylation occurs?

#8

Yes. In it’s established that there’s always going to be side reactions occurring - reactions with oxygen, solvent, two THC(A) molecules coming together, etc. However, @Sunslabs I don’t believe we know the identity of the other ‘decarboxylation products’. I doubt all of them would be desirable.

If you have access to pure THCA and an analytics company that you trust, try taking pure THCA and decarboxylating it. Unless you find the absolute magical conditions, I am sure you won’t get the purity of the resulting THC to match or exceed the THCA purity.

Although, there are definitely ways to get more than the .68 d9THC conversion that @srihugh1 is reporting. I’ve around 95% (so 0.95 * 0.877 in terms of mass) (keeping in mind that the analytical results will have some error in them).

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#9

I used to decarboxylate quinolines back in 2016. I would never see high yields since the temperature to decarb was around 180 *C. This is about where you start seeing radicals come in and do work.

A typical radical reaction is:
Initiation
Propagation
Termination

Now the problem with radicals is that you cannot really control what they do. The initiation step is where a radical is formed. Propagation step involves a radical making a new radical. The termination step is where two radicals form a new bond and the reaction is done.

Now look at propagation. Literally anything can happen here. You typically make a carbon soup and try to purify what you can out of it. It would be advantageous to start looking at transition metals to help with the decarboxylation step.

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#10

I was recently getting a consistent 83-85% from
ethanol-extracted THC crude though I wasn’t measuring how much was already decarboxylated or how much residual solvent. Rotos were only running at 65°C so there may have been a small amount of both. The lowest empirical data I’ve heard of on THC crude was around 80-81% I believe (which I believe lines up with my lowest numbers).

Someone try it with pure THCa crystals, under deep vacuum, please.

#11

You can prove it to yourself.
If you have an HPLC:

  1. Inject the THCA standard to verify it is really 100% THCA and has not already decarboxylated in storage. If you don’t see a d9THC peak then its OK.
  2. Calibrate on a d9THC standard ( the Restek synthetic 100% decarbed standard ).
  3. Externally decarb the THCA by evaporating 100ul of the methanol solvent ( the THCA comes in methanol ) and then heating the residue at 150C for 20 minutes. You can try decarbing at other temperatures for comparison. If you heat too hot for too long you will make CBN.
  4. Re-dissolve the decarbed residue in an equal volume ( 100ul ) of clean methanol and then inject into the HPLC. You should see a d9THC peak only, no THCA. Since you are calibrated for d9THC you will get an answer. I predict that answer will be the .68 number.

If you have a GC:

  1. Derivitize the THCA standard and inject to verify that it has not decarbed. If you don’t see a d9THC peak then its OK.
  2. Externally decarb the THCA standard as with the HPLC above.
  3. Calibrate on d9THC
  4. Inject the externally decarbed THCA and get the result. I predict it will be .68.

See this explanation from Steep Hill Labs in CA. Its not very clearly stated, but if you read it they say that they get a 75% conversion efficiency after the 12.3% mass loss from the decarbing. So they have the formula where they first multiply the THCA result by .877 and then multiply that by the 75% efficiency number to get .66.


Its worth noting that in most states, the law requires the HPLC lab to multiply the THCA number by .877 and then add that to the d9THC result to get the “total smokable potency”. They are not allowed to use the real number. Why you might ask. It may have to do with generating the highest possible result.

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#12

Thanks for the in depth analysis!

I believe that decarboxylation procedure you’re describing can be optimized, though. 150 C is far hotter than necessary, and as @wc15 said, at higher temperatures radicals are going to mess up your yields. I believe it can be optimized to get a 95% conversion, or 83% mass balance.

@wc15 did you notice anything that you could change to improve your yields? Solvent degassing and running the experiment under vacuum, for example? I imagine if you were able to lower the temperature that would help. I have read on here that you can add MgO (food grade) and CaO powders to lower your decarb temperatures as low at 90C. Anyone have experience with that?

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#13

If you can achieve a better yield then that’s great, but in terms of the test results you get from a 3rd party lab you can see how they are biased depending on the multiplication factor the lab uses. If you compare the test results from a GC and HPLC, the GC number gives you the real answer because the GC decarbs the sample according to the .68 while the HPLC number is fictional.

#14

I would decarb in deuterated water back then. It would apply here.

I can design an experiment for this when I get back into a lab.

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#15

PM me for a derivitization SOP.