which is why, by default, most labs won’t attach said chromatogram. one also injects only enough analyte to HIT your LOQ. any more would be trying too hard.
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True, this would not be the absolute limit of quantitation for the method, gc fid can probably go down to ~100ppm before quantities are not reproducible. A better term for it would be Practical Quantitation Limit (PQL), as in a quantitation limit relative to the safety threshold- PQL at 50% of state’s safety threshold. Which is common practice in impurities screening in cannabis and pharma.
But if you ask the lab and say it’s for Rnd and you want trace level results, they should be able to quantify much lower.
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As far as I know, we have never sold any Cortland gas. I know for sure that the gas @MWCanna is referring to was not from Cortland.
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phuck that
Does any of these observations seem remotely familiar?
THCA is “cognate derivative” of Salicylic Acid.
???CHALKING PROCESS???
Publication Date:June 1, 2021
https://doi.org/10.1021/acs.cgd.1c00399
We report a ripening mechanism in crystallization of an organic compound that is observable above 1 μm and is different from Ostwald ripening. Salicylic acid crystallized in methanol and water in the presence of simulated structurally similar impurities resulted in impurity entrapment via the formation of solid solutions. Impurities were retained in the solids to a higher degree in the early part of the crystallization and decreased rapidly toward the end. This uneven impurity entrapment resulted in impurity gradients in individual crystals, which were detected and confirmed by Raman imaging. The impurity entrapment impacted the physical properties of salicylic acid, including its solubility and melting properties. An intra-particle thermodynamic driving force was thus found to exist during the crystallization, which caused selective dissolution of the dirtier cores of the crystal and recrystallization on the cleaner edges. These concomitant but opposing mass transfer processes during the crystallization were responsible for the formation of hollow crystals of salicylic acid. The ripening phenomenon is demonstrated experimentally in the beginning and end of an isothermal anti-solvent crystallization as well as during an agitated filter dryer operation.
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Hollow!!
So @Kingofthekush420 CAN has the amethysts he wants?!?
CBD quinone seems an awful lot like a “structurally similar impurity”…
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Brings the entire “cannabinoic acid” repertoire into “concert.”
But I am wondering why Pub Chem lists salicylic acid-methanol
As a compound or complex. Perhaps Photon will think about this.
“solid solutions”…when/where will all this end…?
WTFamines…and Willbilly “Duhs”…are we gaining knowledge
In the sense that we now know we will never understand?
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Acetylate that and watch it go pink
There’s definitely different colors based on how oxidized the cannabinoids are.
I love weed, its so very simple yet infinitely intriguing, far out maan!
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Considering how many people perform MeOH winterization I’m also surprised with the LOQs here. I believe USP 467 threshold is only 300ppm and we validate our labs’ methods to 20% of action level (so 60 ppm). We also found GCMS to be necessary to reach appropriate sensitivity and also cut down on false positives for certain analytes (for instance there is a heptane isomer that coelutes with benzene on most GC methods and requires separation via MRM).
As far as removing MeOH from butane, simple LLE ought to work pretty well. Just going to take a bunch of drying afterwards. I’d say just fill a tank with a dip tube with water, pressurize to get the BP of the tane above freezing, inject liquid tane through dip tube and recover the vapor from the headspace. Assuming MeOH that is codistilling is low concentration (<0.1%) it ought to knock the concentration down a couple orders of magnitude. You could even add any gas phase adsorption to the recovery/dry with molseive at the same time.
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If you are worried about amines as well why not acidify water, protonate the amine to R-NH3…and remove everything in a single step…?
2 cent idea if you’re designing a scrubber.
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Wrong thread?
I’m starting to think that the really bad fast crash certain people are experiencing is caused by the trace amount of methanol mixing with water in the solvent creating a strong anti solvent effect . Depending on solvent tank temperature there could be trace amounts of water mixed with methanol and this is preventing it from freezing like it normally would if it was just butane . All it takes is such a small amount of water and the thca will fast crash . We all know this from back in the shatter days having slabs nucleate from small amounts of moisture . I have also seen people mist freshly poured Pyrex with water and have dry sugar done in 4 hours from pour . This would also explain why some people replace with fresh solvent and it temporarily fixes the issue . I think this is the cause of the rapid crash in the collection pot and when all the thca just drops out within 15-20 mins of pouring .
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Yea that’s kinda what I’ve been thinking. I’ve had runs back in the day when sieves didn’t get changed that looked like fast crash but would go away right after changing the sieve.
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It’s amazing to me how much collaborative learning there is going on. It feels like the lights just came on and we’re all seeing things that were there, but in the dark. I’m so impressed by the work that going on here. I wish I could just bring in a big tray of snacks. Great job, friends.
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One of the clues was that (essentially) this method does in fact seem to remediate the gas…
Is that the 20yr old GCMS you got up and running? Might have to follow in your footsteps.
The 50 year old HP 5840 that just landed in my lap might be more work than it’s worth (manual seem “rare” at best), but getting a mass spec up would be really useful.
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Nearly EVERYTHING in the abstract here has a corollary in the medusa issue…
crystallized in methanol and water in the presence of simulated structurally similar impurities (Lewis Adduct: THCa-amine is a “structurally similar impurity”)
resulted in impurity entrapment via the formation of solid solutions (THCa alternating with THCa-amine adduct)
Impurities were retained in the solids to a higher degree in the early part of the crystallization and decreased rapidly toward the end (“Catalytic” crystallization mechanism)
impurity entrapment impacted the physical properties of salicylic acid, including its solubility and melting properties (Medusa-petrified THCa crystals are harder to dissolve & melt than typical THCa crystals)
An intra-particle thermodynamic driving force was thus found to exist during the crystallization, which caused selective dissolution of the dirtier cores of the crystal and recrystallization on the cleaner edges (Using higher temperatures can AVOID medusa/fast-crash, even in contaminated solvent)
concomitant but opposing mass transfer processes during the crystallization were responsible for the formation of hollow crystals (“Chalky” THCa crystals are POROUS)
Thanks for the paper, @moronnabis!
I also like your “amine as crystallization enhancer” idea! It might be easier for folks to comprehend than my calling it a “catalytic” process… Yours is a more macroscopic & temporal view where my version is a more microscopic & instantaneous snapshot. To wit, I consider the Lewis adduct to be an intermediate of an unknown but obviously brief lifespan, so this is essentially the same concept, but explained a little differently. Awesome! 
So yeah, @Dukejohnson … This is another way to see it!
Full paper:
wang2021.pdf (10.9 MB)
Diagram of theory from paper:
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Thank you @Photon_noir, this alternative view helps my brain grok the chemistry much better, does the dissolution of the impurities accelerate when a hysteresis of heat is cycled ? The variable always being temperature due to evaporative cooling and atmospheric pressure changes
I bring this up because @Waxplug1 has been expressing his lack of spotting bad gas in other threads and I want to imagine this could be from cycling temps and pressures at a more consistent or slower rate ?
Just a thought
Thx for the gnarly article man 
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It’s not happening in the pot or pour outs either. I wish it did, it would greatly speed up my process
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If by “running” you mean “it makes chromatograms” then yes! If you mean I’ve gotten around to actually doing any quantification with it then no. Unfortunately it got back burnered right after I bought two more lol
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