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Quantifying cannabinoids for label accuracy is a major goal of testing, though calculation and testing processes may vary slightly from state to state. Despite any differences, laboratorians generally agree that when testing for cannabinoids such as THC and CBD, as well as their respective biosynthetic precursors THCA and CBDA, the methodology used must be scrutinized. The naturally occurring THCA of cannabis isn't psychoactive; it requires [[decarboxylation]] (a chemical reaction induced by drying/heating that releases carbon dioxide) to convert itself into the psychoactive cannabinoid THC. Chemical calculations show that the process of decarboxylation results in approximately 87.7 percent of the THCA's mass converting to THC, with the other 12.3 percent bubbling off as CO<sub>2</sub> gas.<ref name="CAWhy1">{{cite web |url=https://www.conflabs.com/why-0-877/ |title=Why 0.877? |publisher=Confidence Analytics |date=10 February 2016 |accessdate=07 July 2021}}</ref> The problem with this in the testing domain is [[gas chromatography]] (GC) involves heating the sample solution. If you, the lab technician, require precise numbers of both THCA and THC, then GC analysis poses the risk of under-reporting THC total values.<ref name="APHLGuide16">{{cite web |url=https://www.aphl.org/aboutAPHL/publications/Documents/EH-Guide-State-Med-Cannabis-052016.pdf |format=PDF |title=Guidance for State Medical Cannabis Testing Programs |author=Association of Public Health Laboratories |pages=35 |date=May 2016 |accessdate=07 July 2021}}</ref> As such, [[Chromatography#Liquid chromatography|liquid chromatography]]-[[Chromatography detector|diode array detection]] (LC-DAD) may be required if a concise profile of all cannabinoids must be made, primarily because it provides environmental stability for them all during analysis. If GC is used, the analysis requires extra considerations such as sample derivatization.<ref name="APHLGuide16" /><ref name="CassidayTheHighs16">{{cite web |url=https://www.aocs.org/stay-informed/inform-magazine/featured-articles/the-highs-and-lows-of-cannabis-testing-october-2016 |title=The Highs and Lows of Cannabis Testing |author=Cassiday, L. |work=INFORM |publisher=American Oil Chemists' Society |date=October 2016 |accessdate=07 July 2021}}</ref><ref name="RigdonAccurateJuly15">{{cite web |url=http://blog.restek.com/?p=14961 |archiveurl=https://web.archive.org/web/20190301212605/http://blog.restek.com/?p=14961 |title=Accurate Quantification of Cannabinoid Acids by GC – Is it Possible? |author=Rigdon, A. |work=ChromaBLOGraphy |publisher=Restek Corporation |date=29 July 2015 |archivedate=01 March 2019 |accessdate=07 July 2021}}</ref><ref name="RigdonAccurateSept15">{{cite web |url=http://blog.restek.com/?p=15135 |archiveurl=https://web.archive.org/web/20180406091114/https://blog.restek.com/?p=15135 |title=Accurate Quantification of Cannabinoid Acids and Neutrals by GC – Derivatives without Calculus |author=Rigdon, A. |work=ChromaBLOGraphy |publisher=Restek Corporation |date=09 September 2015 |archivedate=06 April 2018 |accessdate=07 July 2021}}</ref>
Identifying and quantifying terpenes is one of the more difficult tasks facing laboratorians<ref name="CassidayTheHighs16">{{cite web |url=https://www.aocs.org/stay-informed/inform-magazine/featured-articles/the-highs-and-lows-of-cannabis-testing-october-2016 |title=The Highs and Lows of Cannabis Testing |author=Cassiday, L. |work=INFORM |publisher=American Oil Chemists' Society |date=October 2016 |accessdate=07 July 2021}}</ref>:


The APHL briefly describes analysis methods of cannabinoids using both LC and GC on pages 31–32 of their May 2016 ''Guidance for State Medical Cannabis Testing Programs''. They also point to New York Department of Health - Wadsworth Center's various guidance documents (MML-300, -301, and -303) for methodologies when testing sample types other than solids, particularly using [[high-performance liquid chromatography]] photodiode array detection (HPLC-PAD).<ref name="APHLGuide16" /><ref name="MML-300">{{cite web |url=https://www.wadsworth.org/sites/default/files/WebDoc/576578963/MML-300-01.pdf |format=PDF |title=Measurement of Phytocannabinoids using HPLC-PAD, NYS DOH MML-300 |author=Division of Environmental Health Sciences, Laboratory of Organic Analytical Chemistry |publisher=New York State Department of Health |pages=34 |date=03 November 2015 |accessdate=07 July 2021}}</ref> Also worth noting is that [[ASTM International|ASTM]]'s Subcommittee D37.03 is working on various standard methods for determining cannabinoid concentrations using different chromatography techniques<ref name="ASTMSubD37.03">{{cite web |url=https://www.astm.org/COMMIT/SUBCOMMIT/D3703.htm |title=Subcommittee D37.03 on Laboratory |publisher=ASTM International |accessdate=07 July 2021}}</ref>, while the Association of Official Agricultural Chemists (AOAC) has already developed a Standard Method Performance Requirement (SMPR) for analyzing cannabinoids in [[hemp]] (i.e., low THC cannabis varieties).<ref name="AOACNew19">{{cite web |url=https://www.aoac.org/news/aoac-cannabinoid-standard-in-usda-guidelines/ |title=New guidelines require laboratories to meet AOAC Standard Method Performance Requirements for Quantitation of Cannabinoids in Hemp |author=Association of Official Agricultural Chemists |work=AOAC News |date=12 November 2019 |accessdate=07 July 2021}}</ref> Overall, methods used in cannabinoid testing include<ref name="APHLGuide16" /><ref name="CassidayTheHighs16" /><ref name="MML-300" /><ref name="LeghissaDetection18">{{cite journal |title=Detection of cannabinoids and cannabinoid metabolites using gas chromatography with vacuum ultraviolet spectroscopy |journal=SSC Plus |author=Leghissa, A.; Smuts, J.; Qiu, C. et al. |volume=1 |issue=1 |pages=37–42 |year=2018 |doi=10.1002/sscp.201700005}}</ref><ref name="SCCann16">{{cite web |url=https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/116/856/cannabis-testing.pdf |format=PDF |title=Cannabis Testing: Quality You Can Trust |publisher=Sigma-Aldritch Co. LLC |date=2016 |accessdate=07 July 2021}}</ref><ref name="AdamsNear16">{{cite web |url=https://cannabisindustryjournal.com/column/near-infrared-gc-and-hplc-applications-in-cannabis-testing/ |title=Near Infrared, GC and HPLC Applications in Cannabis Testing |author=Adams, T.; Bertone, M. |work=Cannabis Industry Journal |publisher=Innovative Publishing Co. LLC |date=30 November 2016 |accessdate=07 July 2021}}</ref>:
<blockquote>Terpenes present an analytical challenge because they are [[Chemical polarity#Nonpolar molecules|nonpolar]] and structurally similar, and many structural [[isomer]]s exist. [[Mass spectrometry]] (MS) cannot distinguish terpenes that co-elute from a GC column because many have the same molecular weight and share fragment ions.</blockquote>


* [[Fourier-transform infrared spectroscopy]] (FTIR; has limitations, such as requiring standard samples tested w/ other methods)
Of course, types of gas chromatography work; but like cannabinoids, terpenes can degrade with the high heat of gas chromatography.<ref name="AdamsNear16">{{cite web |url=https://cannabisindustryjournal.com/column/near-infrared-gc-and-hplc-applications-in-cannabis-testing/ |title=Near Infrared, GC and HPLC Applications in Cannabis Testing |author=Adams, T.; Bertone, M. |work=Cannabis Industry Journal |publisher=Innovative Publishing Co. LLC |date=30 November 2016 |accessdate=07 July 2021}}</ref> Combined with the problems mentioned above, highly specialized gas chromatography processes that include additional steps, such as full evaporation technique headspace gas chromatography flame ionization detection (FET-HS-GC-FID), can be used to produce cleaner results, particularly for volatile components.<ref name="CassidayTheHighs16" /> It's less clear if high-performance liquid chromatography (HPLC) is used frequently; some entities such as Eurofins Experchem Laboratories claim HPLC works best for them<ref name="AdamsNear16" />, while others such as Restek Corporation claim the method is problematic at best.<ref name="HerringCanHP16">{{cite web |url=https://blog.restek.com/?p=33071 |archiveurl=https://web.archive.org/web/20190412051141/https://blog.restek.com/?p=33071 |title=Can HPLC-UV Be Used For Terpenes Analysis In Cannabis? |author=Herring, T. |work=ChromaBLOGraphy |publisher=Restek Corporation |date=29 December 2016 |archivedate=12 April 2019 |accessdate=07 July 2021}}</ref>
* Gas chromatography-flame ionization detection (GC-FID; requires sample derivatization for both acid and neutral compounds; good with standards like 5α-cholestane, docosane, and tetracosane)
* [[Gas chromatography–mass spectrometry]] (GC-MS; requires sample derivatization for both acid and neutral compounds; good with standards like deuterated cannabinoids)
* [[Gas chromatography–vacuum ultraviolet spectroscopy]] (GC-VUV)
* High-performance liquid chromatography photodiode array detection (HPLC-PAD; stable for all forms of cannabinoids)
* High-performance liquid chromatography UV detection (HPLC-UV)
* [[Supercritical fluid chromatography]] (SFC; newer technology w/ added benefits)
* [[Thin-layer chromatography]] (TLC; older, less common technology)
* [[High-performance liquid chromatography#Pump pressure|Ultra-performance chromatography]] (UPC; newer technology w/ added benefits)


Also worthy of note is recent investigation of viably using [[Nuclear magnetic resonance spectroscopy|nuclear magnetic resonance (NMR) spectroscopy]] as a more affordable and rapid solution to identifying cannabinoid contents and profiles of samples. Conferences<ref name="ZilerRecap19">{{cite web |url=https://www.spectralservice.de/recap-of-the-first-nmr-cannabis-meeting/?lang=en |title=Recap of the First NMR Cannabis Meeting |author=Zailer, E. |publisher=Spectral Service AG |date=02 January 2019 |accessdate=07 July 2021}}</ref>, research<ref name="WangComp17">{{cite journal |title=Comparative Study of NMR Spectral Profiling for the Characterization and Authentication of Cannabis |journal=Journal of AOAC International |author=Wang, X.; Harrington, P.B.; Baugh, S.F. |volume=100 |issue=5 |pages=1356–64 |year=2017 |doi=10.5740/jaoacint.17-0089 |pmid=28718398}}</ref><ref name="MarchettiUseOf19">{{cite journal |title=Use of <sup>13</sup>C-qNMR Spectroscopy for the Analysis of Non-Psychoactive Cannabinoids in Fibre-Type Cannabis sativa L. (Hemp) |journal=Molecules |author=Marchetti, L.; Brighenti, V.; Rossi, M.C. et al. |volume=24 |issue=6 |pages=1138 |year=2019 |doi=10.3390/molecules24061138}}</ref><ref name="SiudemRapid19">{{cite journal |title=Rapid evaluation of edible hemp oil quality using NMR and FT-IR spectroscopy |journal=Journal of Molecular Structure |author=Siudem, P.; Wawer, I.; Paradowska, K. |volume=1177 |pages=204–08 |year=2019 |doi=10.1016/j.molstruc.2018.09.057}}</ref>, and articles<ref name="MayNMR17">{{cite web |url=https://www.analyticalcannabis.com/articles/nmr-spectroscopy-producing-a-chemical-fingerprint-of-cannabis-292728 |title=NMR Spectroscopy: Producing a chemical fingerprint of cannabis |author=May, M. |work=Analytical Cannabis |date=28 September 2017 |accessdate=07 July 2021}}</ref><ref name="BennettCanna18">{{cite web |url=https://www.leafly.com/news/science-tech/why-test-cannabis |title=Cannabis Testing Explained: What’s in Your Cannabis? |author=Bennett, P. |work=Leafly |date=31 December 2018 |accessdate=07 July 2021}}</ref><ref name="ConnCanna19">{{cite web |url=https://pittcon.org/cannabis-trends-in-analytical-research/ |title=Cannabis: Trends in Analytical Research |author=Conn, P. |publisher=The Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy, Inc |date=14 March 2019 |accessdate=07 July 2021}}</ref> over the last few years have advanced the use of NMR spectroscopy for cannabinoid analysis.
Overall, methods for terpene identification and analysis include<ref name="CassidayTheHighs16" /><ref name="SCLabs">{{cite web |url=https://www.sclabs.com/terpene-analysis/ |title=Terpene Analysis |publisher=SC Labs, Inc |accessdate=07 July 2021}}</ref><ref name="SCCann16">{{cite web |url=https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/116/856/cannabis-testing.pdf |format=PDF |title=Cannabis Testing: Quality You Can Trust |publisher=Sigma-Aldritch Co. LLC |date=2016 |accessdate=07 July 2021}}</ref><ref name="HodgsonVacuum18">{{cite journal |title=Vacuum Ultraviolet Spectroscopy: A New Tool for Gas Chromatography Analysis of Terpenes in Flavours and Fragrances |journal=LC GC |author=Hodgson, A.; Cochran, J. |volume=14 |issue=2 |pages=12–16 |date=12 February 2018 |url=https://www.chromatographyonline.com/view/vacuum-ultraviolet-spectroscopy-new-tool-gas-chromatography-analysis-terpenes-flavours-and-fragrance}}</ref><ref name="AdamsNear16" /><ref name="ShimadzuCLTS">{{cite web |url=https://www.ssi.shimadzu.com/products/literature/life_science/shimadzu_cannabis_brochure.pdf |archiveurl=https://web.archive.org/web/20160327180816/https://www.ssi.shimadzu.com/products/literature/life_science/shimadzu_cannabis_brochure.pdf |format=PDF |title=Cannabis Testing Laboratory Solutions |publisher=Shimadzu Corporation |archivedate=27 March 2016 |accessdate=07 July 2021}}</ref><ref name="CEMAnal18">{{cite web |url=https://www.azom.com/article.aspx?ArticleID=16383 |title=Analyzing Pesticide Residue of Cannabis |author=CEM Corporation |work=AZO Materials |publisher=AZoNetwork |date=25 July 2018 |accessdate=07 July 2021}}</ref>:
 
* Full evaporation technique–headspace–gas chromatography–flame ionization detection (FET-HS-GC-FID; tends to be semi-quantitative)
* Gas chromatography–flame ionization detection (GC-FID)
* Gas chromatography–mass spectrometry (GC-MS)
* Gas chromatography–vacuum ultraviolet spectroscopy (GC-VUV)
* [[Headspace gas chromatography for dissolved gas measurement|Headspace–gas chromatography]]–mass spectrometry (HS-GC-MS)
* Headspace–solid-phase microextraction (HS-SPME)
* High-performance liquid chromatography (HPLC; may have limitations due to coelution of terpenes and cannabinoids at certain ranges<ref name="HerringCanHP16" />)


==References==
==References==
{{Reflist|colwidth=30em}}
{{Reflist|colwidth=30em}}

Revision as of 20:43, 4 February 2022

Identifying and quantifying terpenes is one of the more difficult tasks facing laboratorians[1]:

Terpenes present an analytical challenge because they are nonpolar and structurally similar, and many structural isomers exist. Mass spectrometry (MS) cannot distinguish terpenes that co-elute from a GC column because many have the same molecular weight and share fragment ions.

Of course, types of gas chromatography work; but like cannabinoids, terpenes can degrade with the high heat of gas chromatography.[2] Combined with the problems mentioned above, highly specialized gas chromatography processes that include additional steps, such as full evaporation technique headspace gas chromatography flame ionization detection (FET-HS-GC-FID), can be used to produce cleaner results, particularly for volatile components.[1] It's less clear if high-performance liquid chromatography (HPLC) is used frequently; some entities such as Eurofins Experchem Laboratories claim HPLC works best for them[2], while others such as Restek Corporation claim the method is problematic at best.[3]

Overall, methods for terpene identification and analysis include[1][4][5][6][2][7][8]:

  • Full evaporation technique–headspace–gas chromatography–flame ionization detection (FET-HS-GC-FID; tends to be semi-quantitative)
  • Gas chromatography–flame ionization detection (GC-FID)
  • Gas chromatography–mass spectrometry (GC-MS)
  • Gas chromatography–vacuum ultraviolet spectroscopy (GC-VUV)
  • Headspace–gas chromatography–mass spectrometry (HS-GC-MS)
  • Headspace–solid-phase microextraction (HS-SPME)
  • High-performance liquid chromatography (HPLC; may have limitations due to coelution of terpenes and cannabinoids at certain ranges[3])

References

  1. ↑ 1.0 1.1 1.2 Cassiday, L. (October 2016). "The Highs and Lows of Cannabis Testing". INFORM. American Oil Chemists' Society. https://www.aocs.org/stay-informed/inform-magazine/featured-articles/the-highs-and-lows-of-cannabis-testing-october-2016. Retrieved 07 July 2021. 
  2. ↑ 2.0 2.1 2.2 Adams, T.; Bertone, M. (30 November 2016). "Near Infrared, GC and HPLC Applications in Cannabis Testing". Cannabis Industry Journal. Innovative Publishing Co. LLC. https://cannabisindustryjournal.com/column/near-infrared-gc-and-hplc-applications-in-cannabis-testing/. Retrieved 07 July 2021. 
  3. ↑ 3.0 3.1 Herring, T. (29 December 2016). "Can HPLC-UV Be Used For Terpenes Analysis In Cannabis?". ChromaBLOGraphy. Restek Corporation. Archived from the original on 12 April 2019. https://web.archive.org/web/20190412051141/https://blog.restek.com/?p=33071. Retrieved 07 July 2021. 
  4. ↑ "Terpene Analysis". SC Labs, Inc. https://www.sclabs.com/terpene-analysis/. Retrieved 07 July 2021. 
  5. ↑ "Cannabis Testing: Quality You Can Trust" (PDF). Sigma-Aldritch Co. LLC. 2016. https://www.sigmaaldrich.com/deepweb/assets/sigmaaldrich/marketing/global/documents/116/856/cannabis-testing.pdf. Retrieved 07 July 2021. 
  6. ↑ Hodgson, A.; Cochran, J. (12 February 2018). "Vacuum Ultraviolet Spectroscopy: A New Tool for Gas Chromatography Analysis of Terpenes in Flavours and Fragrances". LC GC 14 (2): 12–16. https://www.chromatographyonline.com/view/vacuum-ultraviolet-spectroscopy-new-tool-gas-chromatography-analysis-terpenes-flavours-and-fragrance. 
  7. ↑ "Cannabis Testing Laboratory Solutions" (PDF). Shimadzu Corporation. Archived from the original on 27 March 2016. https://web.archive.org/web/20160327180816/https://www.ssi.shimadzu.com/products/literature/life_science/shimadzu_cannabis_brochure.pdf. Retrieved 07 July 2021. 
  8. ↑ CEM Corporation (25 July 2018). "Analyzing Pesticide Residue of Cannabis". AZO Materials. AZoNetwork. https://www.azom.com/article.aspx?ArticleID=16383. Retrieved 07 July 2021. 
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