Myrcene, linalool, limonene, caryophyllene, and another one hundred plus aromatic compounds found in cannabis are known as terpenes. As science is now revealing, there is more to these molecules than meets the eye. [1]
Terpenes are the magic elements behind the amazing cannabis fragrances that influence customer preferences. They also offer therapeutic benefits and are at the heart of cannabis entourage or ensemble effects. What is emerging is that cannabis terpenes are pivotal to the success of medicinal cannabis, which predominantly centers on cannabinoids (mostly tetrahydrocannabinol, THC, and cannabidiol, CBD).
With such an important role to play, the analysis of cannabis terpenes is of key importance in the advancement of medicinal cannabis.
How are cannabis terpenes analyzed?
One recent study sought to investigate the challenges and opportunities in the analysis of cannabis terpenes. [2]
The industry standard for analysis is chromatography. This may include thin layer chromatography (TLC), gas chromatography (GC), or liquid chromatography (LC). However, GC works best for terpenes because they are volatile compounds. This can be paired with a flame ionization detector (FID), which is a low-cost option to record retention times. Mass spectrometry (MS) is more expensive but provides superior quantitation. Headspace (HS) has proven an effective technique as well.
The researchers reported that though common, chromatographic methods are time-inefficient, skill-intensive, and require expensive equipment.
For comparison, the researchers looked at alternative methods such as infrared spectroscopy and chemometric methods. They also looked at method fragmentation and multiplicity as well as arising legal issues.
In keeping with new regulations, labs may need to analyze for pesticides and other compounds. Liquid chromatography and tandem mass spectrometry (LC-MS/MS) may be superior to GC when analyzing a complex matrix.
Fourier transform infrared spectroscopy (FTIR; a type of absorption spectroscopy) may enable the speedy analysis of terpenes. FTIR spectrometers are third-generation infrared spectrometers with very high signal-to-noise ratio and resolution. They have mostly been used for cannabinoids, however. [3]
Chemometrics, which has been widely used in the analysis of different compounds, may also have applications in the analysis of terpenes. [4] Chemometrics refers to an “interdisciplinary method of analytical chemistry in which trends are extracted from data sets.” This typically relies on GC due to terpene volatility and may be coupled with FTIR.
Nuclear spectroscopy methods such as nuclear magnetic resonance (NMR) can also help to identify and quantify secondary metabolites in cannabis. NMR detects the electromagnetic signals from the nucleus of a molecule. This can improve the efficiency of cannabis testing and presents a non-invasive method that is cheap, fast, and does not compromise on accuracy or throughput. [5]
Method fragmentation/multiplicity largely refers to differences in sample preparation techniques across labs. The researchers recommend that testing labs should have a trained analytical chemist to minimize variances in testing results.
The researchers concluded that advances in spectroscopic miniaturization and the “genomic, molecular and biomolecular properties that define terpenes” could lead to breakthroughs on the analysis of cannabis terpenes. [2]
Image Source
bdyczewski via Pixabay
References
- Cox-Georgian D, et al. Therapeutic and medicinal uses of terpenes. In: Joshee N, Dhekney S, Parajuli P, eds. Medicinal Plants: From Farm to Pharmacy. 2019:333–359.
- Rodney T, et al. (2021). Challenges and opportunities for the analysis of terpenes in cannabis. Undergraduate Journal of Teaching and Research. 2021:2691-6495. [Impact Factor: n/a; Times Cited: n/a]
- Smith B, Fucetola C, Ehrmantraut K, Hagan T. “Quantitation of CBD and THC in MCT Oil by Mid-Infrared Spectroscopy,” Terpenes & Testing Magazine, Sept-Oct 2020.
- Orser C. “Cannabis Chemometrics: Converting Untargeted Data to Knowledge,” Terpenes & Testing Magazine, Sept-Oct 2020.
- Hazekamp A, et al. Quantitative analysis of cannabinoids from Cannabis sativa using 1H-NMR. Chemical & Pharmaceutical Bulletin. 2004;52:718–21. [Impact Factor: 1.416; Times Cited: 75 (Semantic Scholar)]
