Method for detection of cannabinoids for gc fid

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

10 posts Page 1 of 1
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
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.
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.
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:
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.
Thank you. The articles are very informative and good written. I was looking for this information, and it helped me a lot.
The best column for this purpose is Restek Rxi-35Sil MS
http://www.restek.com/chromatogram/view/GC_FS0527
The method involves trimethyl silyl derivatization of the extracts. These cannabinoids include tetrahydrocannabivarian, CBD, cannabichromene, trans-Δ8-tetrahydrocannabinol, Δ9-THC, cannabigerol, cannabinol, cannabidiolic acid, cannabigerolic acid, and Δ9-tetrahydrocannabinolic acid-A. The concentration-response relationship of the method indicated a linear relationship between the concentration and peak area ratio with R2 > 0.999 for all 10 cannabinoids. The precision and accuracy of the method were found to be ≤ 15% and ± 5%, respectively. The limit of detection range was 0.11 - 0.19 µg/mL, and the limit of quantitation was 0.34 - 0.56 µg/mL for all 10 cannabinoids. The developed method is simple, sensitive, reproducible, and suitable for the detection and quantitation of acidic and neutral cannabinoids in different extracts of cannabis varieties. The method was applied to the essay expert analysis of these cannabinoids in different parts of the micropropagated cannabis plants (buds, leaves, roots, and stems).
Hello, please see brief information with regards to a method of analysis for Cannabinoids using a GC-FID-SQMS below:

Please drop me a word at sunny.singh@scioninstruments.com for the full method - and I can send a pdf across.

The analysis of cannabinoids from biological matrices
is made easy with the SCION GC MS The highly
sensitive and robust instrument has exceptional limit
of detection for both Δ 9 THC and THC COOH With an
LOD of 0 2 ng/mL and LOQ of 0 5 ng/mL, for Δ 9 THC,
these limits exceed the requirements specified by the
laws in UK, Canada and France Additionally, the
cannabinoid analyser is capable of detecting THC
COOH at concentrations as low as 2 5 ng/mL, with
excellent repeatability for both cannabinoids
REFERENCES
FWIW, I've been working with the "low budget and portable" option of using an SRI 8610C with a Restek 15m MXT-1 .530M column.

Using H2 as a carrier, I can get reliable separation and quantification of CBD, THC, and CBN in ~5 minutes with an FID. I do a 260ºC isothermal run with 2psi of column pressure(on column injection).

I haven't done any "real world" samples, but SRI markets this sort of set-up for exactly the sort of application it's been configured-namely a field-portable instrument for quick testing of grown products.

In Kentucky, agricultural hemp is capped at I think .7% THC, and this system is set up to quickly and easily ensure compliance. Since hemp growers also want to maximize CBD content, this information is given also.
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