The complexities associated with new psychoactive substances in influent wastewater: The case of 4-ethylmethcathinone.

Consumption of new psychoactive substances (NPS) is an international problem for health, policing, forensic, and analytical laboratories. The transience of these substances in the community, combined with continual slight structural changes to evade legislation makes the elucidation of NPS an analytical challenge. This is amplified in a matrix as complex as wastewater. For that reason, suspect and non-target methodologies, employing high resolution mass spectrometry are the most appropriate current tool to facilitate the identification of new and existing compounds. In the current work, a qualitative screening method of influent wastewater using liquid chromatography-high resolution mass spectrometry showed a strong signal at m/z 192.1382 - identical to that of two NPS standards that were in our method (pentedrone and 4-methylethcathinone), and with identical fragment ions, but the retention times did not match. This work shows the methodology followed to identify this compound, highlighting the challenges of the identifying "new" compounds in influent wastewater.