With airline tickets costing what they do these days, I’m surprised you only charge 5k
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This was years ago and travel was usually invoiced at cost.
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Why is HPLC testing a waste if the lab shows the chromatograms when I ask and each time the peaks are extremely and clearly separated between D8 and D9?
Is there some reason I can’t trust an HPLC chromatogram that has clear separation?
Are you saying the separation will be even more resolved if GC is used instead?
And how can MS help if D8 and D9 have the same weight?
I guess I am wishing that there is a “For 5-year olds” explanation of why GCMS is so important to proper D8 testing when, every time I ask the lab for a chromatogram on a D8 product COA, the resolution always looks great. Unless someone can tell me why I should ignore a great looking chromatogram, it is difficult to digest the idea that all these labs that have some kind of special sauce on their D8 testing have anything to offer at all other than perhaps interesting research.
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The CBD isomerization reaction creates D9 and D8 via one pathway and the iso-THC compounds on a separate pathway. D4,8-iso-THC coelutes with D9-THC and D8-iso-THC coleutes with D8 on reverse phase HPLC. Inflated concentrations are easily reported, including a higher D9 value. On methods with poor separation four analytes can look like one, typically D8 since it’s highest in concentration.
GC and normal phase HPLC can achieve separation between all four compounds, so that they are quantified separately from each other.
We use triple quadrupole mass spec, which allows for fragmentation to be used in characterizing a compound.
Here is a paper we wrote on the issue: Challenges_in_Determining_Delta-8-THC_in_Cannabidiol_Conversion_Products_040522.pdf (634.3 KB)
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What do you estimate as a great resolution ?
Could you show some example please ?
I believe FID is sufficient for this work.
MS brings a little more confidence in the fact that the analytes are THCs (or something that weigh and fragment similarly…) and not something totally different.
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Because they fragment differently.
Edit: reasonably sure that requires tandem or triple MS, but that is what most labs are running these days.
Very few running old school “Mass Specific Dectectors”: I bought a thing!: Adventures with a 20-year-old GCMS
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main fragment of d8 is 231, main fragment of d9 is 299.
however, the ‘unknown’ byproducts of the rxn have some fragmentation patterns that aren’t in any literature I was able to find. and I looked everywhere.
the most interesting ones are those that had a primary fragment at 277. I assumed this was the isopropyl group blasting off of the iso-THC’s, but since the standards of those don’t really exist (@kcalabs any update on standard procurement for these?) it was more guesswork and less validation from the literature
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Yes, they’re available at Cayman now
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since I’m no longer pursuing the project, could you tell me what cannabinoids that you all have ‘discovered’ with a primary fragment at 277 m/z? i’m really just interested in why/how the structure would fragment that way!
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We don’t see any with a primary fragment at 277. Do you have one in mind? It probably isn’t a cannabinoid.
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In my experience they do not fragment differently on MS/MS. Tried lots of different collision settings and could not see any difference. I’d love to see some difference in fragments though if anyone has seen it.
Also, single quad ms still has its place in ID of cannabinoids (obviously not isomers though). I like em still because no molecular pump required and they are generally more robust (not as picky about impurities, less moving parts = more uptime) also they are like 3x smaller than a tqd.
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I’ve got zero. with MS. MS/MS or smashy/smashy/smash. except for filling the later with liquid N2 or He once upon a time.
hoping to change that.
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I run an ion trap that can definitely do MRM (basically only quantifying certain mass peaks), I’m not sure if standard quadrupole mass specs can do that standard. I believe they can. Triple quad can run quantification on the major fragments and then smashes the resulting ions again and you can quantify the sub-parts which makes for much more decisive identification of what exactly is coming through. You might have a completely unresolved peak when doing total ion count, but then you can go back and look at the peaks for the spectra of the compounds you’re looking for (d8 and d9 respectively) and you basically ignore the signal from the one you’re not looking for.
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Sid, have you seen a difference in fragmentation of d8 VS d9? Like what are the transitions you are seeing? I would love to discuss. Maybe it would be better done in another thread though to avoid this dumpster fire.
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interesting. I was using an agilent 6890 with a 5973msd for reference. 30cm capillary column, He carrier gas, RT of d8 and d9 at like 6.8min vs 7.1min (CBD at 6.3 for reference). MW was 314.
I assumed from Harvey '87 that the fragmentation pattern could be due to the isopropyl group on C6 leaving on iso-THC’s due to the methyl group on C11 being less susceptible than the isopropyl in the iso-THCs, but I could never find the MS data for the iso-THCs or the majority of compounds listed as byproducts in the toxics papers from 2021.
Given the relatively high abundance of 2 compounds with a primary m/z of 277, especially in more thermodynamically unstable environments, iso-THC isomer soup was the best guess I could come pup with.
I can’t believe I’m discussing MS fragmentation patterns on a thread called Pegasus Tears on an industry forum with the most respected analytical lab in the US. Our industry needs some sort of peer-reviewed platform where educated discussions and review doesn’t happen alongside whatever the hell this thread is.
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I’m going to double check with my analyst to make sure he is including the iso-THCs in that review of m/z.
The iso-THCs elute close to CBD on our method and I think we have a bit more resolution between them.
I agree about the discussion. Maybe we can get this split off.
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Its called a free for all, good sir
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Thanks for the split!!
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thank you 
I personally don’t have any real data regarding d8/9 fragmentation, honestly KCA is the authority in my eyes. They were able to perform some d8/9 THCV quantification for us and I was extremely impressed by the resolution they were able to get. Peaks were almost 100% overlapped with some unknowns before doing an ion screen
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