Analytical Methods Used for Identification and Determination of Synthetic Cathinones and Their Metabolites

Abstract

Synthetic cathinones are a broad group of chemicals, which have very similar structure. Many substances seized from the drug market are isomers, homologues, analogues, etc. They follow similar metabolism processes, and often convert in the human body to the same metabolites; some being also cathinone derivatives. Moreover, active doses differ significantly among drugs, causing that the levels of cathinones and their metabolites in the body fluids and tissues are in a broad range, from low ng/mL to hundreds mg/L. A variety of analytical techniques is applied to identify synthetic cathinones in seized drugs. Unequivocal identification of an active substance is crucial, especially in countries with individual drug control system, as the legal consequences for, e.g. possession of different isomers may vary substantially. Gas chromatography–mass spectrometry (GC-MS) is the most commonly method used for preliminary identification in forensic laboratories, but it has to be supported by other techniques, e.g. by Fourier-transformed infrared spectrometry (FTIR), nuclear magnetic resonance (NMR) and liquid chromatography with different detectors, mainly tandem mass spectrometers. Synthetic cathinones are analysed in different biological matrices, including blood, serum, plasma, dried blood spots, urine, hair, oral fluid and postmortem body tissues. Samples are prepared for the analysis, e.g. by dilution, precipitation, liquid–liquid extraction (LLE) and solid phase extraction (SPE). Enzyme hydrolysis (especially for urine), washing out or digestion (for hair), and derivatization are also included in some procedures. Triple quadrupole LC-MS/MS systems are the most frequently used. Many analytical challenges cause that more sophisticated techniques, including liquid chromatography-high-resolution mass spectrometry (LC-HRMS), are increasingly applied in the analysis of biological materials for the identification and quantitation of cathinones.