Can anyone identify these unknown isomers in my chromatagram. The lab we used said it was a very unique sample with more cannabinoids in it that they dont have standards for yet.
It’s very difficult to identify unknown peaks from just a chromatogram.
To begin to be able to do that, it’s important to know the details of the chromatographic method. Then you might get lucky that someone is running a similar method and has identified those peaks.
Otherwise more information is needed. If the detector is a PDA, the UV-Vis spectrum of the unknown peaks could possibly be used to help determine the type of molecule. If it’s an MS detector the mass spectrum can be helpful in identifying the molecular ion and thus molecular weight.
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I doubt it. Without knowing exactly how it was run, those retention times are not particularly informative. @MagisterChemist or @AlexSiegel might manage an informed guess.
Without the spectral data from the various channels, IDing from retention time alone is prone to misidentification.
You might also tell us what you did to it, rather than make folks guess.
Because specific “unknowns” are known to come for the ride in specific use cases.
Edit: and some other @idiot beat me to it 
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They used HPLC-PDA for the analysis.
What is the sample ?
The column, solvent, and method set up (temperature, pressure, flow) are the most relevant informations.
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Yeah, but that tell us nothing about the solvent system or method run, both of which affect retention times.
See: Chromatogram: 3% THC
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There is no way to identify based on this. Even if we had the full method information it wouldn’t be possible to do with much confidence. As the lab themselves said, these are rare peaks they’ve never seen before – the odds someone is out there using this exact same method, produced these same peaks, and then got secondary analysis by NMR or something on them is pretty much nill.
A potentially more useful approach might be to tell us what sort of chemistry you did to produce all these peaks – then maybe someone might be able to speak from experience of having done similar reactions and at least give an educated guess.
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Surprisingly I may have familiarity with most of this if you can answer one question, was this test done at KCA?
This chromatogram is very zoomed in.
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The significant unknowns are CBG isomers as far as we know.
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Well a collorfull chromatogram is never a good thing to see.
Would you elaborate based on what are you guessing on CBG isomers?
Is the original extract oredominantely CBG?
I can t help identifying but I am very curious as to what isomerization was attempted to get these results ?
CBC ?
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I would recommend an example of their “QC High” and noting the retention times of all the cannabinoids they report. Based on the lack of separation between D8 and D9 THC and the order of your chromatogram, I suspect they are running an acetonitrile organic phase with some sort of additive ( 0.1 % TFA, 0.1% Formic Acid, etc) and of course, an aqueous mobile phase.
I would be curious to know the retention times for two reasons.
- Keep in mind that the HPLC is not just used for cannabinoid potency analysis. For example, technicians use caffeine to confirm the system is set up correctly. There may be a compound(s) that are eluding at a similar time to the cannabinoids. Melatonin is an example of one of those compounds. By getting an example of a QC High you may be able to conclude that some sort of non-cannabinoid are causing these peaks.
- If the two peaks to the right of D9 are cannabinoids, the most likely culprits are CBC or THC-A. However, your lab hasn’t called that which makes me think that the retention times differ slightly from what I would expect. By getting a marked-up image that details their cannabinoid profile via a QC High, you will be more able to eliminate the more common cannabinoids.
I also wouldn’t hesitate to ask them to rerun the sample for confirmation. Sample prep error is a common mistake in analytical testing labs.
I hope that helps!
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I’ll have the team run on GC-MS (I’m 90% sure they already did) and send chromatograms to @zboyd to post since it’s his data.
We ran this sample a couple times already given the inherent curiosity of the chemists trying to identify these peaks.
@Ganjane, we believe them to be cannabinoids. They’re not any of the ones listed on the COA (we run an internal marker to detect any shift) and none of the others we have standards for.
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EXO-thc is the peak directly in front of delta 9
Method independent?!?
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Have you tried utilizing an LC/MS/MS if you have one?
Yeah, we have methods on both LC-MS/MS and GC-MS/MS. Just as @Dr_Jebril predicted, we ended up running into some coelution issues on the LC, so the GC method has been in constant development the last month or two.
I’ll ask to run on both, which they may already have. They’re usually several steps ahead of me…probably reading this post, haha.
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