Identification of cathinones and other active components of ‘legal highs’ by mass spectrometric methods

The supply of psychoactive substances has changed and users increasingly buy “legal highs” over the Internet or in specialized shops. Vast arrays of preparations are marketed as legal substitutes to controlled substances. Their analysis has revealed that the majority of active components belong to one of four chemical classes: phenethylamines, tryptamines, piperazines and cathinones, the last being novel.This article gives special attention to cathinone derivatives and certain characteristic fragmentations based on the GC-EI/MS and LC-ESI/QTOF-MS spectra. The parent ions of these substances are hard to obtain by EI/MS, whereas the protonated molecular ions can be observed clearly by ESI/QTOF-MS. Furthermore, two major characteristic α-cleavages are produced when the EI mode is used, leading to formation of iminium and acylium ions, respectively. These ions can process secondary and tertiary fragmentations, which are very useful in identification. In the case of ESI/QTOF-MS, characteristic fragments are produced via loss of water in cathinones, being secondary amines.The targeted MS/MS mode allows us to identify structures of many unknown substances with certainty. Nevertheless, in order to determine the location of a substituent in a molecule, it is sometimes necessary to use NMR or FTIR.Problems found in identifying novel recreational drugs sold as “legal highs” indicate the need for international collaboration and sharing knowledge and analytical data amongst experts from forensic and clinical laboratories.

► I analyzed mass spectral behaviors of substances found in “legal highs”. ► A general scheme for identifying chemical class of unknown substance uses GC-EI/MS. ► I discussed the fragmentation of cathinones under EI/MS and ESI/QTOF-MS.