Analyzing Cannabinoids Using Mass Spectrometry

By Rebecca Ingle, Ph.DMay 16 2022

Cannabinoids are compounds found in the Cannabis sativa plant and interact with the endocannabinoid system. Cannabinoids are the family of compounds therefore responsible for many of the intoxicating and medical properties of the extracts from cannabis plants.

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With cannabis derivatives such as cannabidiol (CBD) increasing in availability and popularity, the Food and Drug Administration has issued new guidance on the safe use of cannabinoid-containing products and the currently unanswered scientific questions surrounding the safety of such products.¹

Understanding the safety and issuing regulations and guidance means having analytical techniques that can be used to identify what ingredients are present in a potential therapeutic product or foodstuff and what concentrations those ingredients are present in.

Natural plant extracts can be complicated to analyze as they are often mixtures of thousands of chemical species. Mass spectrometry is one tool that offers the sensitivity and selectivity to deal with many of the challenges that the emerging cannabis industry faces, including identifying product origins from isotope ratios, forensic toxicology and regulatory compliance on any contaminant chemical species.²

The mass spectrometry techniques used to analyze cannabinoid profiles and concentrations are often hyphenated methods such as liquid chromatography-mass spectrometry (LC-MS).³ Hyphenated methods such as LC-MS use a chromatographic column to separate analytes by their retention time before performing mass spectrometry on each separated analyte for a more selective analysis and greater confidence in species identification. LC-MS and the sample preparation required are also highly compatible with examining samples of urine and saliva.³

Cannabinoids

Two of the primary natural cannabinoids found in Cannabis sativa include trans-Δ9-tetrahydrocannabinol (THC), the psychoactive ingredient in cannabis, and CBD. There are now several prescription products that are legal worldwide that contain either THC, CBD, or combinations thereof that are used for dealing with neuropathic and chronic pain conditions and other conditions including suppression of nausea during chemotherapy treatments.⁴

There are also now a number of synthetic cannabinoids being explored for their medical properties but they have also become used as a new class of recreational drugs. The appeal of synthetic cannabinoids, many of which have greater potencies than the cannabinoids found naturally in Cannabis sativa and, with careful tuning of the chemical structure, can be modified to deliver specific medicinal or psychoactive effects.⁵

Mass Spectrometry for Cannabinoid Analysis

Both families of cannabinoids can be analyzed with mass spectrometry methods. One way to identify the presence of chemical compounds with a known structure, such as THC and CBD, is to use mass spectrometry methods with very high mass resolution.⁶

A typical mass spectrometry experiment consists of an ionization source, an acceleration/deflection region for mass separation, and a detector to output the final signal.

First, the sample needs to be ionized and often vaporized to produce the charged species that can be deflected by the electromagnetic fields in the mass spectrometer.

The electromagnetic fields can guide and separate the ions by their mass. The amount of deflection depends on the mass of the target ion and the mass spectrometer's design, which either results in a different flight time, and, therefore, arrival time at the detector, or a different position of arrival on the detector.

Often the ionization process in the source region also causes some degree of molecule fragmentation. Depending on the amount of excess energy the molecule receives during the ionization step, the amount of fragmentation of the parent molecule changes.

While the mass of the parent ion is often used for species identification of a particular cannabinoid, the fragmentation patterns also contain helpful information about the chemical structure. They are often also characteristic of a specific chemical species and so can improve confidence in the assignment. Fragmentation patterns can also be beneficial when dealing with the identification of novel cannabinoids.

With the use of calibration standards, mass spectrometry can be used as a quantitative technique alongside its qualitative capabilities and with its good sensitivity, used to detect even trace amounts of cannabinoids and potentially their metabolites.

Real-Time Detection

While many countries are now starting to reduce the legislation around the use and manufacture of cannabinoids, there are still many countries where their use remains heavily restricted.⁴ As consumption or possession of many cannabinoids is a legal issue in many countries, methods that can rapidly detect the presence of these compounds is needed.

Many mass spectrometry variants, such as direct analysis in real-time (DART) mass spectrometry, are ideal for rapidly detecting and identifying such compounds.^{7 ­­}Many methods, especially those that use ambient ionization, require little sample preparation and can be used in the field for measurements. Field instruments can also be operated with minimal training.

One of the main challenges for the use of mass spectrometry in the cannabis industry, particularly for pharmaceutical applications, is dealing with the complexity and number of chemical species in the data analysis.⁸ However, advances in chemometrics methods and more advanced separation techniques will help with this challenge in the future.

References and Further Reading

1. FDA (2022) Regulation of Cannabis. [Online] Available at: https://www.fda.gov/news-events/public-health-focus/fda-regulation-cannabis-and-cannabis-derived-products-including-cannabidiol-cbd, accessed May 2022
2. Nie, B., Henion, J., & Ryona, I. (2019). The Role of Mass Spectrometry in the Cannabis Industry. Journal of the American Society for Mass Spectrometry, 30(5), 719–730. https://doi.org/10.1007/s13361-019-02164-z
3. Grauwiler, S. B., Scholer, A., & Drewe, J. (2007). Development of a LC/MS/MS method for the analysis of cannabinoids in human EDTA-plasma and urine after small doses of Cannabis sativa extracts. Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences, 850(1–2), 515–522. https://doi.org/10.1016/j.jchromb.2006.12.045
4. Brown, J. D., Rivera Rivera, K. J., Hernandez, L. Y. C., Doenges, M. R., Auchey, I., Pham, T., & Goodin, A. J. (2021). Natural and Synthetic Cannabinoids: Pharmacology, Uses, Adverse Drug Events, and Drug Interactions. Journal of Clinical Pharmacology, 61(S2), S37–S52. https://doi.org/10.1002/jcph.1871
5. Grigoryev, A., Savchuk, S., Melnik, A., Moskaleva, N., Dzhurko, J., Ershov, M., Nosyrev, A., Vedenin, A., Izotov, B., Zabirova, I., & Rozhanets, V. (2011). Chromatography-mass spectrometry studies on the metabolism of synthetic cannabinoids JWH-018 and JWH-073, psychoactive components of smoking mixtures. Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences, 879(15–16), 1126–1136. https://doi.org/10.1016/j.jchromb.2011.03.034
6. Grabenauer, M., Krol, W. L., Wiley, J. L., & Thomas, B. F. (2012). Analysis of synthetic cannabinoids using high-resolution mass spectrometry and mass defect filtering: Implications for nontargeted screening of designer drugs. Analytical Chemistry, 84(13), 5574–5581. https://doi.org/10.1021/ac300509h
7. Ji, J., Wang, J., & Zhang, Y. (2021). Rapid screening of 23 synthetic cannabinoids in blood by direct analysis in real time - Tandem mass spectrometry. International Journal of Mass Spectrometry, 469, 116667. https://doi.org/10.1016/j.ijms.2021.116667
8. Bechysnka, K. et al, (2021) Cannabis Metabolomic Data Processing, [Online] Available at: https://www.chromatographyonline.com/view/cannabis-metabolomic-data-processing-challenges-to-be-addressed, accessed May 2022

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