Pitfalls in the analysis of phytocannabinoids in cannabis inflorescence

The chemical analysis of cannabis potency involves the qualitative and quantitative determination of the main phytocannabinoids: Delta(9)-tetrahydrocannabinol (Delta(9)-THC), cannabidiol (CBD), cannabigerol (CBG), cannabichromene (CBC), etc. Although it might appear as a trivial analysis, it is rather a tricky task. Phytocannabinoids are present mostly as carboxylated species at the aromatic ring of the resorcinyl moiety. Their decarboxylation caused by heat leads to a greater analytical variability due to both reaction kinetics and possible decomposition. Moreover, the instability of cannabinoids and the variability in the sample preparation, extraction, and analysis, as well as the presence of isomeric forms of cannabinoids, complicates the scenario. A critical evaluation of the different analytical methods proposed in the literature points out that each of them has inherent limitations. The present review outlines all the possible pitfalls that can be encountered during the analysis of these compounds and aims to be a valuable help for the analytical chemist.