Differentiation between drug-type, fibre-type and intermediate-type in cannabis samples: HPLC-UV versus GC-FID

Cannabis sativa is known to be the most abused illegal drug worldwide. To date it is not only used as a medicine but has been established as a lifestyle product. The most relevant phytocannabinoids represent the ingredients delta-9-tetrahydrocannabinol (9-THC) and cannabidiol (CBD), whereby only 9-THC shows a psychoactive effect. Since 2017, the so-called CBD-hemp containing CBD as main ingredient is distributed in many countries as a legal alternative. In these products, 9-THC must not exceed a certain percentage. It is hardly possible to differentiate between THC-hemp and CBD-hemp presenting a major challenge for authorities. Therefore, there is the need to develop fast and efficient analysis methods to distinguish between fibre-type, drug-type and intermediate-type cannabis products. The aim of this study was to compare two simple and inexpensive HPLC-UV and GC-FID methods for their ability to quantify phytocannabinoids in dried cannabis plant material. For this purpose, a set of 37 fresh and dried cannabis samples randomly chosen from seizures of Austrian police was subject to complementary quantification of 9-THC and CBD. After having taken into account decomposition of certain phytocannabinoids, the result of this quantitative study showed good correlation between HPLC-UV and GC-FID regardless of quantifying cannabis leaves or buds.