CANNABINOID PROFILE AND HEMP PLANTS’ CHEMOTYPE BY USING LC-FTICR / MS AND TANDEM MASS SPECTROMETRY PERFORMED BY IRMPD AND CID

Certainly no member of the vegetable kingdom has ever been more misunderstood than hemp and many debate were carried out about the distinction between industrial hemp and marijuana. Botanically, the genus Cannabis is the only plant genus that contains the unique class of molecular compounds called cannabinoids, a group of terpenophenolic secondary metabolites (1). Between all cannabinoids two are the main: Δ9-Tetrahydrocannabinol (THC), which is the psychoactive ingredient of Cannabis, and cannabidiol (CBD), which is an anti-psychoactive ingredient (1). Marijuana is the type of Cannabis containing high level of THC (5-20%) and a low level of CBD. Hemp, on the contrary, is high in CBD and low in THC, and it is used in industrial applications. Only products obtained from industrial hemp can be legally sold, bought, consumed, and shipped (3); so it is very important to determine the level of different cannabinoids, in particular the THC/CBD ratio that identify the chemo-type, in each plant destined to human consumption. The balance of cannabinoids is determined by the genetics of the plant, which it is a stable characteristic of a given genotype (4). To identify the kind and the amount of cannabinoids, liquid chromatography coupled with electrospray ionization (LC/ESI) and Fourier-transform ion cyclotron resonance mass spectrometry (FTICR MS) was applied, and the chemo-type of different hemp plants obtained by varietal selection and destined to food industry was determined. Structural information were obtained upon fragmentation of precursor ions [M+H]+ within the high resolution trapping cell by infrared multiphoton dissociation (IRMPD) (Fig.1a) and low resolution MSn experiments performed by collisional induced dissociation (CID) (Fig.1b). High resolution IRMPD spectra exhibit several diagnostic product ions with a mass accuracy lower than 0.7 ppm. Generally, cleavage of the aliphatic chain, ring opening and water loss constitute the major fragmentation pathways for most of the protonated compounds. FTICRMS analyses showed that the variety of cannabis analyzed is a CBD chemo-type that can be used in food industry, confirming the success of the phenotypic selection. The applied method was also able to identify and quantify minor cannabinoids, which characterize specifically the analyzed plants.