Fragmentation of synthetic cannabinoids with an isopropyl group or a tert-butyl group ionized by electron impact and electrospray.

This study described a fragmentation pattern of 21 synthetic cannabinoids with an isopropyl group or a tert-butyl group by electron impact ionization quadrupole mass spectrometry and electrospray ionization time-of-flight mass spectrometry in the positive mode. The compounds were categorized into four types according to substituted group such as a terminal amide and ester. The characteristic fragment ion in each group was obtained. The main common fragment ions for the two ionizations were formed by C-N cleavage of the amide group adjacent to the N-hetero rings. Additionally, the fragment ions indicated the difference in the basic structure as well as substituted group, which are useful for estimating the chemical structures of unknown compounds.