Utilizing derivatizing agents for the differentiation of cannabinoid isomers in complex food, beverage and personal-care product matrices by ambient ionization mass spectrometry

Recent legalization and decriminalization of marijuana at the state level has not only contributed to a rise in the recreational use of Cannabis sativa, also known simply as Cannabis, but also to an increase in the range of matrices into which cannabinoids derived from it are infused. Traditional methods for analyzing these products, which are typically chromatography-based, are often matrix-dependent and demand time-consuming and resource-intensive sample preparation protocols that are highly nuanced and not readily applicable to multiple matrix types. Furthermore, the differentiation of cannabinoids can be troublesome without implementing lengthy run times to achieve resolution of chromatographic peaks. With complex samples such as edibles, beverages, personal-care products, and plant materials, a method that can be more universally applied to rapidly detect and differentiate between cannabinoids is highly desirable. In this study, foods and personal-care products under the categories of sweets, spreads, condiments/toppings, beverages, oils, and commercial body products were spiked with cannabinoids including Δ⁹-tetrahydrocannabinol (THC), cannabidiol (CBD), cannabicitran (CBT), and cannabigerol (CBG). Chemical derivatization of the samples with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) followed by direct analysis in real time – high-resolution mass spectrometry (DART-HRMS) analysis readily revealed the presence of cannabinoids in the products despite the matrix complexity (i.e., the contributions from matrix-derived peaks did not interfere with the differentiation of cannabinoids). When analyzed under ambient soft ionization conditions, CBT, THC and CBD are indistinguishable because they are isomers with a molecular formula of C₂₁H₃₀O₂ and a protonated monoisotopic mass of 315.2324. However, due to the different number of hydroxyl (-OH) groups (zero in CBT, one in THC, and two in CBD) that engage with the derivatizing agent, the cannabinoids are differentiated based on the mass disparities of the protonated adducts formed (m/z 315.2324, 387.2719 and 459.3119 for CBT, THC, and CBD, respectively), which is readily revealed by DART-HRMS. This approach circumvents some of the challenges currently encountered by forensic laboratories in the analysis of highly complex and diverse cannabinoid-infused matrices. The results show proof-of-concept for an approach that can aid in the differentiation of cannabinoid isomers by DART-HRMS that accommodates high matrix diversity and complexity, and demonstrates the potential for the approach to be integrated into current workflows for the forensic analysis of Cannabis-related materials and evidence.