Establishment of a Mass Spectrometric Fingerprint of the Most Common Phytocannabinoids in Electrospray Ionization in Positive Ion Mode.

Abstract

Analysis of the phytocannabinoids holds significant importance because of their various pharmacological properties and potential therapeutic applications. Tandem mass spectrometry (MS/MS) coupled with electrospray ionization in positive ion mode is employed in this study to describe the collision-induced dissociation (CID) behavior of a series of common phytocannabinoids with the aim of establishing a generalized MS/MS fingerprint. Eight phytocannabinoids, namely, ∆9-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabichromene (CBC), cannabigerol (CBG), tetrahydrocannabivarin (THCV), 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC), 6-hydroxy-cannabidiol (6-OH-CBD), and 7-hydroxy-cannabidiol (7-OH-CBD), were studied. A Quadrupole-Orbitrap mass spectrometer equipped with a heated electrospray ionization (HESI-Q Orbitrap) is used to provide accurate mass measurement data for single-stage and MS/MS analysis. In addition, a triple quadrupole-linear ion trap mass spectrometer was used to perform MS/MS and second-generation MS/MS (MS3) analyses. An abundant, singly charged [M + H]+ species during single-stage MS analysis was observed for all phytocannabinoids, with mass accuracies less than 5 ppm. Because of their structural similarities, all compounds showed some common fragmentation behavior in their MS/MS analysis. By comparing the fragmentation patterns and identifying diagnostic ions, a universal MS/MS fragmentation pattern was established. The structures of the various product ions proposed in the fragmentation pathway were confirmed with exact mass measurements and MS3 experiments. The evaluated compounds contain varying functional groups, resulting in unique product ions, specific to each structure. The MS/MS fingerprints will be utilized in the future for the identification of new structures as well as the development of targeted quantification methods.