Novel, rapid and sensitive detection of isomeric fluorinated new psychoactive substance(s) and their principal metabolites using analytical techniques

In the last few years, there has been a remarkable increase in the prevalence and use of New Psychoactive Substances (NPS) within the global recreational drugs market. The biological activity of NPS, formally known as “legal highs”, exhibit similarities to illicit drugs of abuse. Different regioisomers, such as those of fluorocathinone, can have different toxicological and biological effects. As such, it is vital to distinguish between their isomers. Therefore, a simple, accessible and selective analytical method is promptly required to differentiate positional isomeric N-substituted fluorocathinones. In this project, a combination of GC–MS, LC-MS, IR, presumptive testing and thin layer chromatography have been employed for full chemical characterization of the regioisomers of cathinone derivatives. GC-MS and LC-MS are essential for the screening of compounds in illicit drug products. The LC-MS spectrum presents information about the molecular weight, and the GC-MS spectrum gives structural information about the molecule. N-alkylated ortho-, meta- and para-fluoroethcathinones were unequivocally separated by GC-MS, using product ion spectrometry of the hydrogen fluoride loss ions. These compounds were also characterized and identified using full analysis of 1H and 13C{1H}, 19F{1H}, 1H-1H COSY, HMQC and HMBC using high-field nuclear magnetic resonance (NMR) spectroscopy. Isomeric fluorinated N-ethylcathinone (FEC) is structurally similar to fluoromethcathinone (FMC) isomers, with only the methyl group at the end of the side chain substituted for an ethyl group. Therefore, J-resolved and HETCOR spectroscopy were employed to resolve the positional regioisomers using low-field bench top NMR (1.4 T). In reality, however, due to similarities in their structures, this was difficult to achieve. It was possible to separate the FEC and FMC isomers within their own class but not an individual FEC/FMC regioisomer from a FEC/FMC mixture.