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Method for detection of cannabinoids for gc fid

Posted: Thu Jan 14, 2016 10:20 pm
by ZEyKiTa
Hi all
Tell you that I am in a dilemma, since I work with forensic toxicology and urgently need a method for detecting cannabinoids and cannabinoid metabolites in various samples. my team is Agilent 7890B GC and my column is HP5-MS UI 30 meters and 0.25 mm in diameter; greatly appreciate it if someone could colaborarme passing me a paper, a method or a link where I can find him. Thank you so much. And sorry if my English is not good and I am from Bolivia and speak Spanish. THANKS. :D :D

Re: Method for detection of cannabinoids for gc fid

Posted: Fri Jan 15, 2016 8:43 pm
by osp001
I believe the compound you will be looking for is 11-nor-9-carboxy-Δ9-tetrahydrocannabinol. Generally the detector used is mass spec, as the ramifications of a false positive can be very serious; unlike the FID, the MS detector is orthogonal: retention time coupled with mass fragments is characteristic of the compound of interest. (Mass fragments alone should be sufficient.)

With that in mind, there are several papers on the subject that can be found via Google Scholar. Some examples:

http://jat.oxfordjournals.org/content/20/6/441.short

http://jat.oxfordjournals.org/content/25/5/289.short

https://www.researchgate.net/profile/Ci ... 3b4511.pdf

If you can get this (rather old) paper, it specifically addresses GC-FID:

http://jat.oxfordjournals.org/content/6/1/49.short

But the caveat stands: anything less than mass spec is not a responsible way to go about it in a legal setting.

Re: Method for detection of cannabinoids for gc fid

Posted: Sat Jan 16, 2016 2:30 pm
by chemstation
Phthalates come out at the same retention time as THC, and as osp001 said, GCMS is the only alternative.

Phthalates have different Ions than THC, so a SIM method using only THC ions produces excellent library matches.

That is how I got around the Phthalate problem from utensils.

Re: Method for detection of cannabinoids for gc fid

Posted: Thu Jan 25, 2018 4:42 pm
by johnson83
osp001 wrote:
I believe the compound you will be is 11-nor-9-carboxy-Δ9-tetrahydrocannabinol. Generally the detector used is mass spec, as the ramifications of a false positive can be very serious; unlike the FID, the MS detector is orthogonal: retention time coupled with mass fragments is characteristic of the compound of interest. (Mass fragments alone should be sufficient.)

With that in mind, there are several papers on the subject that can be found via Google Scholar. Some examples:

http://jat.oxfordjournals.org/content/20/6/441.short

http://jat.oxfordjournals.org/content/25/5/289.short

https://www.researchgate.net/profile/Ci ... 3b4511.pdf

If you can get this (rather old) paper, it specifically addresses GC-FID:

http://jat.oxfordjournals.org/content/6/1/49.short

But the caveat stands: anything less than mass spec is not a responsible way to go about it in a legal setting.


Thank you very much :mrgreen:

Re: Method for detection of cannabinoids for gc fid

Posted: Tue Mar 27, 2018 8:24 am
by pumpedupchemist
I work in forensic toxicology myself. The only way for reliable and reportable results is with Mass Spec and even then the results can be variable batch to batch.

From blood the THC needs to be extracted using solid phase extraction.

We have recently had development using LC-MS/MS but only for qualitative purposes.

Re: Method for detection of cannabinoids for gc fid

Posted: Thu May 24, 2018 12:47 pm
by AliceJ11
Thank you. The articles are very informative and good written. I was looking for this information, and it helped me a lot.

Re: Method for detection of cannabinoids for gc fid

Posted: Mon Jun 04, 2018 8:40 pm
by ant78se
The best column for this purpose is Restek Rxi-35Sil MS
http://www.restek.com/chromatogram/view/GC_FS0527