Fragmentation pathways of α-pyrrolidinophenone synthetic cathinones and their application to the identification of emerging synthetic cathinone derivatives

Abstract

The expanding use of emerging synthetic drugs is creating a growing problem for both seized drug analysts and toxicologists because the clandestine suppliers continually tweak the chemical structures to keep one step ahead of the law. Synthetic cathinones, commonly referred to as bath salts, are a specific class of emerging synthetic drugs. These substances are derivatives of cathinone, which is the psychoactive component of the Catha edulis plant, commonly referred to as khat. Of the synthetic cathinone class of compounds, the α-pyrrolidinophenone synthetic cathinone derivatives stand out as one of the most abused designer drugs.The fragmentation behavior of a series of α-pyrrolidinophenone synthetic cathinones was studied with three different ionization and fragmentation techniques to enhance the current understanding of α-pyrrolidinophenone synthetic cathinones in mass spectrometers. Gas chromatography-electron ionization-mass spectrometry (GC-EI-MS) fragmentation is commonly used by seized drug analysts, whereas liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) is more commonly used in toxicological analyses. Direct analysis in real time mass spectrometry (DART-MS) is becoming more popular as a screening technique, especially in national laboratories. Each ionization and activation method encourage particular pathways of fragmentation, and whereas some pathways are conserved across all platforms, other pathways are unique to a particular instrument. This study combines isotope-labeling, multi-stage mass spectrometry (MSn) and accurate mass measurements with high-resolution mass spectrometry (HRMS) to enhance the current understanding about α-pyrrolidinophenone synthetic cathinones. This manuscript provides characteristic protonated tandem mass spectrometry fragmentation pathways and the mechanistic origins of the EI-MS fragmentation observed for this class of synthetic cathinones and provides examples of how this knowledge can be applied to the identification of novel synthetic cathinones.