Cannabis is a plant with an outstanding chemical profile. Therapeutically interesting pharmacological ingredients are terpenes and cannabinoids. Cannabinoids can be found in the viscous resin that is produced by glandular structures called trichomes. The most abundant phytocannabinoids are tetrahydrocannabinol (THC), cannabidiol (CBD), cannabigerol (CBG), cannabichromene (CBC) and cannabinol (CBN).
In the plant itself, they exist in the form of carboxyl acids. In the body, carboxyl acids have different pharmacological effects than their decarboxylated forms, so most cannabis preparations are being decarboxylated before use. Terpenes are volatile substances that give aroma to the cannabis plant and also have biological effects. Terpenes and cannabinoids work in synergy.
Potential for treatment with cannabis is undoubtedly great, but to establish optimal treatments, chemical profile of the preparations needs to be as clear as possible.
Apart from terpenes and cannabinoids, as in every other plant, cellulose, lignin and chlorophylls, proteins, amino acids, hydrocarbons, alkaloids and other nitrogen-containing compounds, enzymes, carbohydrates, flavonoids, fatty acids, phytosterols, carotenoids, vitamins, minerals and other substances are present. They can be partially of fully removed in the process of extraction, depending on the chosen method.
Some procedures for preparing the extracts include use of unhealthy solvents, insufficient extraction or insufficient decarboxylation. Cannabis users are often mislead or not aware what to expect from their product. Cannabis products should be standardised on their cannabinoid contents, which means their potency should be known. Potency testing is especially important in edibles, because the therapeutic effect arises more than half an hour after consumption and can act for hours.
New cannabis strains are constantly being developed. Their increasing offer means increasing diversity of cannabinoid profiles. Moreover, cannabis plants can fluctuate through various stages of plant growth. Even with stable strains, it is very difficult to ensure stable cannabinoid content. Constituent of synthetic medicines are verified in detail. They are certified to be of high quality, effective and safe. And so should be cannabis preparations of natural origin.
In Freyherr, we developed our own HPLC method for analysis of 8 cannabinoids and GC-MS method for analysis of terpenes. We analyse cannabis in every stage of growth and production.
Analysis of cannabinoids and terpenes can employ different chromatographic procedures. In chromatography, the samples are prepared and injected on the column. They separate as they travel through the column with different paces, which depends on their chemical structures. Finally, they are detected and quantified. There are three common, but highly-sophisticated analytical instruments: Gas chromatography–mass spectrometry (GC-MS), High-performance liquid chromatography (HPLC) and Liquid chromatography–mass spectrometry (LC-MS). Those instruments require highly educated and trained personnel.
GC-MS is the most appropriate method for analysis of volatile compounds, such as terpenes, but is not the most suitable for precise detection of cannabinoids. GC-MS does not detect THCA or CBDA directly. Under high temperature exposure, carboxyl groups decarboxylate and a typical GC-MS output is solely a total amount of CBD and CBDA or THC and THCA. This problem can be solved with derivatisation, which is time consuming and includes steps that increase possibility for errors.
On the other hand, HPLC is the method of choice for analysing cannabinoids. Well-developed HPLC method should separate every cannabinoid, which enables analysis of acid components, THCA and CBDA without conversion to THC and CBD. But is not the most appropriate to analyze volatile terpenes.