Identification and structure characterization of five synthetic opioids: 3,4-methylenedioxy-U-47700, o-methyl-acetylfentanyl, 2-thiophenefentanyl, benzoylfentanyl and benzoylbenzylfentanyl

Abstract

Purpose: The number of new synthetic opioids, especially fentanyl analogs, on the illicit market is increasing each year and becoming a disturbing phenomenon. Due to the very high potency, ease of addiction and high risk of overdose with the fatal effect, they pose a serious threat to public health. The ever-changing drug market, lack of reference standards and low doses make this class of new psychoactive substances (NPS) a continual analytical challenge in terms of detection and identification. Structure elucidations of five synthetic opioids are described in this paper. Methods: Unequivocal identifications were performed using liquid chromatography–high resolution tandem mass spectrometry with quadrupole time-of-flight analyzer (LC–QTOF-MS/MS) and nuclear magnetic resonance (NMR) spectroscopy with prior chromatographic purification of the sample in each case. Results: Identified NPS included one non-fentanyl opioid belonging to “U-compounds group”—3,4-methylenedioxy-U-47700 and four fentanyl analogs: o-methyl-acetylfentanyl, benzoylfentanyl, 2-thiophenefentanyl and benzoylbenzylfentanyl. Conclusions: Complementary LC–QTOF-MS/MS and NMR techniques enabled the unambiguous identification of new synthetic opioids. To the best of our knowledge, this is the first comprehensive characterization of these five NPS with complete data which are published to facilitate their detection and identification by forensic and clinical laboratories.