Merging Science With Nature

Terpenes, (pronounced TUR-peen) is the chemical that produces the aroma associated with cannabis and other plants (e.g. lemon, hops, sage, etc.).  They are organic Hydrocarbons (C₅H₈) synthesized in the secretory cells located inside the glandular trichomes, the same glands where THC is produced (3).  Production of terpenes, along with other cannabinoids, is increased with light exposure (6). Terpenes are mostly found in high concentrations in unfertilized female cannabis flowers as male plants produce few glandular trichomes and therefore few cannabinoids and terpenes.  Some terpenes are more volatile than others, however many vaporize around the same temperature as THC (which boils at about 157°C).

The scent of cannabis results from 140 different terpenoids (terpenes which have been chemically modified) (2). Over 100 terpenes can be produced by Cannabis and as many as 40 have been found in a single plant (3). Many are found in only trace amounts but others may comprise 10 to 20 percent of the total oils produced by the trichome glands and make up about 10 to 29 percent of marijuana smoke resin (8). The age, maturation, and time of day can affect the amount and ratios of terpenes (5). Terpenes are constantly being produced but are vaporized by heat and light of the day.  Cannabinoid content in finished flowers is extremely inhomogeneous allowing for variability of terpene profiles between batches (4). The same variety, even genotype, can produce a different terpene profile determined by growth in different soils, growth with different fertilizers, or simply by flower ripeness (7). This occurs because terpenes are produced by biosynthetic pathways that are turned on and off by genetically determined enzyme systems (3). This means, profile variation is determined by which genes of terpenoid biosynthesis are up regulated or “turned on” (1). Determination of the mechanisms of gene expression may someday lead to a more consistent profile. 

Importantly, terpenes play a significant role in the medicinal and therapeutic effects of cannabis. They can affect circulatory and muscular systems, interact with neurological receptors, alter the permeability of cell membranes allowing absorption of chemicals, and affect serotonin and dopamine chemistry (neurotransmitters). Terpenoids are currently added to bronchial inhalers and cough suppressants to stimulate the membranes of the pulmonary system, soothe the pulmonary passages, and facilitate the absorption of other compounds (3).

TESTING STRATEGIES:                                 

Deibel Bioscience is currently testing for over 20 terpenes of interest to the cannabis industry as shown in Table 1. The testing for these important chemicals is mandated as part of the Dec 31, 2018 phase-in testing scheme as directed by the California Bureau of Cannabis Control (BCC). Although the actual tests that are mandated have not been defined; nor has any guidance been given to the testing labs for the recommended methods and equipment. 

Deibel Cannabis Labs utilize of a Gas Chromatography instrument with a Mass-spec detector (GC-MS) for Terpene testing.  Based on BCC guidance, the allowable limits for a passing batch are within a 10% range of the label claim for the terpene in question.

References

1. Booth, J. K., J. E. Page, J. Bohlmann, and B. Hamberger. 2017. Terpene synthases from Cannabis sativa. PLoS ONE. 12(3): e0173911. Available at: https://doi.org/10.1371/journal.pone.0173911. Accessed 9 January 2019.
2. Brenneisen, R. 2007. Chemistry and analysis of phytocannabinoids and other cannabis constituents, p. 17-49. In M. A. ElSohly (ed.), Marijuana and the Cannabinoids, 1st Ed. Humana Press, Totowa, NJ.
3. Clarke, R. C., and D. P. Watson. 2007. Cannabis and natural cannabis medicines, p. 1-15. In M. A. ElSohly (ed.), Marijuana and the Cannabinoids, 1st Ed. Humana Press, Totowa, NJ.
4. Giese, M. W., M. A. Lewis, L. Giese, and K. M. Smith. 2015. Method for the analysis of cannabinoids and terpenes in cannabis. Journal of AOAC International. 98:1503-1522.
5. Meier, C., and V. Mediavilla. 1998. Factors influencing the yield and the quality of hemp (Cannabis sativa L.) essential oil. Journal of the International Hemp Association. 5:16-20. Available at: http://www.druglibrary.org/olsen/hemp/iha/jiha5107.html. Accessed 9 January 2019.
6. Potter, D. J., and P. Duncombe. 2012. The Effect of electrical lighting power and irradiance on indoor-grown cannabis potency and yield. Journal of Forensic Sciences. 57:618-622.
7. Sexton, M., and J. Ziskind. 2013. Sampling cannabis for analytical purposes. Available at: https://lcb.wa.gov/publications/Marijuana/BOTEC%20reports/1e-Sampling-Lots-Final.pdf. Accessed 9 January 2019.  
8. Vogeler, J. Terpenes and Terpenoids in Cannabis. Available at: http://terpenes.weebly.com/index.html. Accessed 8 January 2019.