Electrochemical profiling and liquid chromatography-mass spectrometry characterization of synthetic cathinones: From methodology to detection in forensic samples.

The emergence of new psychoactive drugs in the market demands rapid and accurate tools for the on-site classification of illegal and legal compounds with similar structures. Herein, a novel method for the classification of synthetic cathinones (SCs) is presented based on their electrochemical profile. First, the electrochemical profile of five common SC (i.e., mephedrone, ethcathinone, methylone, butylone, and 4-chloro-alpha-pyrrolidinovalerophenone) is collected to build calibration curves using square wave voltammetry on graphite screen-printed electrodes (SPEs). Second, the elucidation of the oxidation pathways, obtained by liquid chromatography-high-resolution mass spectrometry, allows the pairing of the oxidation products to the SC electrochemical profile, providing a selective and robust classification. Additionally, the effect of common adulterants and illicit drugs on the electrochemical profile of the SC is explored. Interestingly, a cathodic pretreatment of the SPE allows the selective detection of each SC in presence of electroactive adulterants. Finally, the electrochemical approach is validated with gas chromatography-mass spectrometry by analyzing 26 confiscated samples from seizures and illegal webshops. Overall, the electrochemical method exhibits a successful classification of SC including structural derivatives, a crucial attribute in an ever-diversifying drug market.