Towards the development of a MALDI/TOF-MS Fingerprint Library for the Identification and Differentiation of Cannabis Extracts

Abstract

The legalization of recreational cannabis in Canada has resulted in an increased interest for research on the plant within the scientific community. Currently in Canada, there is no requirement for the confirmation of cultivar/strain identity for cannabis that is sold in recreational distributors. Strains of cannabis differ through their chemical make-up which result in different pharmacological effects. The aim of this research is to develop a method using sequential extraction and matrix assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) and Brukers BiotyperTM software that uses cannabis extracts to fingerprint and distinguish strains purchased from the recreational market. Cannabis was first extracted sequentially using methanol, acetonitrile and hexane to obtain a range of biomolecules from cannabis. Using a methanol extract, BiotyperTM software was optimized to generate peak lists that would include the maximum number of distinguishable peaks in the desired mass range. Then, using generated score values and dendrograms, MALDI mass spectra of strain extracts were compared. It was found that the spectra of the methanol and acetonitrile extracts contained previously observed peaks that are consistent with cannabinoids. Also, some consistent patterns could be found using the methanol and acetonitrile extracts from cannabis. The use of hexane as an extracting solvent was less practical as it is not miscible with the optimized matrix solution. Biotyper software was sometimes consistent but overall showed discrepancies for how peaks were matched. Further work for this research includes the use of tandem mass spectrometry (MS/MS) to determine if matched pairs of peaks are truly identical. Another avenue for future work is method exploiting high iii molecular weight (MW) cannabis proteins for fingerprinting instead of low MW compounds as described in this work.