Direct Quantitation of Phytocannabinoids by One-Dimensional 1H qNMR and Two-Dimensional 1H-1H COSY qNMR in Complex Natural Mixtures

The widespread use of phytocannabinoids or cannabis extracts as ingredients in numerous types of products, in combination with the legal restrictions on THC content, has created a need for the development of new, rapid, and universal analytical methods for their quantitation that ideally could be applied without separation and standards. Based on previously described qNMR studies, we developed an expanded H-1 qNMR method and a novel 2D-COSY qNMR method for the rapid quantitation of ten major phytocannabinoids in cannabis plant extracts and cannabis-based products. The H-1 qNMR method was successfully developed for the quantitation of cannabidiol (CBD), cannabidiolic acid (CBDA), cannabinol (CBN), cannabichromene (CBC), cannabichromenic acid (CBCA), cannabigerol (CBG), cannabigerolic acid (CBGA), Delta 9-tetrahydrocannabinol (Delta 9-THC), Delta 9-tetrahydrocannabinolic acid (Delta 9-THCA), Delta 8-tetrahydrocannabinol (Delta 8-THC), cannabielsoin (CBE), and cannabidivarin (CBDV). Moreover, cannabidivarinic acid (CBDVA) and Delta 9-tetrahydrocannabivarinic acid (Delta 9-THCVA) can be distinguished from CBDA and Delta 9-THCA respectively, while cannabigerovarin (CBGV) and Delta 8-tetrahydrocannabivarin (Delta 8-THCV) present the same H-1-spectra as CBG and Delta 8-THC, respectively. The COSY qNMR method was applied for the quantitation of CBD, CBDA, CBN, CBG/CBGA, and THC/THCA. The two methods were applied for the analysis of hemp plants; cannabis extracts; edible cannabis medium-chain triglycerides (MCT); and hemp seed oils and cosmetic products with cannabinoids. The H-1-NMR method does not require the use of reference compounds, and it requires only a short time for analysis. However, complex extracts in H-1-NMR may have a lot of signals, and quantitation with this method is often hampered by peak overlap, with 2D NMR providing a solution to this obstacle. The most important advantage of the COSY NMR quantitation method was the determination of the legality of cannabis plants, extracts, and edible oils based on their THC/THCA content, particularly in the cases of some samples for which the determination of THC/THCA content by H-1 qNMR was not feasible.

Automated summary

The widespread use of phytocannabinoids or cannabis extracts in various products, coupled with legal restrictions on THC content, has made it necessary to develop new, rapid, and universal analytical methods for quantifying them. In this study, an expanded H-1 qNMR method and a novel 2D-COSY qNMR method were developed for the rapid quantitation of ten major phytocannabinoids in cannabis plant extracts and products.