Cannabis Methods

Discussions about GC and other "gas phase" separation techniques.

7 posts Page 1 of 1
Hi all,
Looking for some general comments/ opinions for my proposed cannabis detection (basic standards to begin with moving to biological samples and actual plant material when optimized). I do not have access to LC-MS.

- Potency of THC total and CBD total to be done by GC-FID
- Residual Solvent Analysis: HS-GC
- Pesticides: GC-MS/ GC-MS/MS
- Samples will be prepared using QuEChERS and SPE clean up

I have experience of quantitating THC in biological samples using GC-MS but found recovery to be variable and not consistent (because of poor SPE technique) with results often being 'present'.
With no access to LC-MS/MS you have severely limited yourself. You cannot analyze many of the common pesticides without LC-MS. You will not be able to determine THCA without LC (UV or MS).

In my opinion it is an absolute necessity for a cannabis laboratory.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
Thanks!!
I haven't tried THCA yet but can do Delta9 and Delta8 THC along with Cannabidiol and Cannabinol using GC/MS SIM with no problems. Right now only doing confirmation of non-detect for the THCs on hemp products so they can be marketed. Just doing extract with Ethyl Acetate and direct injection. Do have to clean out the injection port after but overall not that bad.
The past is there to guide us into the future, not to dwell in.
Delta-8 and Delta-9 are fine; THCA falls apart in the injector port. The problem comes in when you try to do a stability study on a formulation. One of the known degradation pathways for cannabadiol is to THCA, so if you can't see it you can't detect the degradation.

If you're just doing purity analysis of CBD, depending on which state you're in, the two THCs are probably sufficient. If you are going to work with any formulators then you are way better off with HPLC methods.
Mark Krause
Laboratory Director
Krause Analytical
Austin, TX USA
Thanks guys,
I know derivitising with BSTFA can help the stability of THCA so think I will try a variety of different methods and see the outcome. Using GC-MS Sim and having a spectral library obviously helps this for controls & biological samples. Think my downfall will just be the potency of actual flowers due to being in the UK.

Thanks again for your opinions, greatly appreciated.
pumpedupchemist wrote:
Thanks guys,
I know derivitising with BSTFA can help the stability of THCA so think I will try a variety of different methods and see the outcome. Using GC-MS Sim and having a spectral library obviously helps this for controls & biological samples. Think my downfall will just be the potency of actual flowers due to being in the UK.

Thanks again for your opinions, greatly appreciated.
You may find this blog post from Restek, covering TMS derivatization of cannabinoids, to be helpful: https://blog.restek.com/?p=15135
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