The Development of a Simple Liquid Chromatography-Precursor Ion Scan-Mass Spectrometry Screening Method for the Detection of Phytocannabinoids in Plant Extracts

Abstract

Screening of major cannabinoids in cannabis-derived extracts is needed when these extracts are applied in pharmacological and biological studies. Precursor ion scan-mass spectrometry (PIS-MS) is a viable approach for the detection and screening of major cannabinoids through characteristic MS/MS fragmentation behavior. A PIS-MS method was developed utilizing electrospray ionization (ESI) operated in the positive ion mode on a triple quadrupole-linear ion trap mass spectrometer (QTRAP 6500). Three cannabis extracts were screened based on established MS/MS fragmentation pattern. Characteristic product ions at m/z 193.1 and 233.1 were optimized for PIS-MS analysis. In addition, tandem mass spectrometry (MS/MS) was performed to aid in the putative identification of unknown cannabinoids, whereas authentic standards were used, when available, to confirm the identity. A quadrupole-Orbitrap (Exploris 240) mass spectrometer equipped with ESI was also utilized to provide accurate mass measurements for single-stage and MS/MS analyses, supporting the proposed structures of cannabinoids and their product ions. PIS-MS complemented with high-resolution mass spectrometry (HRMS) analysis revealed the existence of six major cannabinoids in two plant extracts, and nine in the third one. Among the detected phytocannabinoids, an unexpected cannabinoid, namely, sesquicannabigerol (Sesqui-CBG), was also identified among the most abundant ones. The MS/MS fragmentation behavior in both positive and negative ionization for Sesqui-CBG was established for the first time, supported by accurate mass measurements and second-generation MS/MS (MS³) experiments. In conclusion, PIS-MS provided an effective approach for the screening of abundant cannabinoids in plant products intended for therapeutic applications. MS/MS and accurate mass measurements confirmed the putative identification of detected cannabinoids. A comprehensive study for Sesqui-CBG was performed, elucidating its fragmentation pathways and product ions.