Investigation of fentanyl transformation in wastewater treatment plant technologies using non-targeted analysis

Fentanyl is a highly potent synthetic opioid that is directly linked to the recent peak in overdose deaths observed in the United States. Increased use of the drug necessarily leads to increased excretion. This has implications for wastewater treatment plant management. Typical treatment technologies have been shown to be ineffective at removing fentanyl and have resulted in other pharmaceuticals transforming into more harmful compounds. In this study, the stability of fentanyl under different wastewater treatment technologies was investigated. Fentanyl was exposed in-vitro to various aqueous media, UV (254 nm) and chlorine (sodium hypochlorite) conditions and analysed through DIA time-of-flight mass spectrometry. Thirty-eight transformation products were tentatively identified with chlorination showing the fastest rate of formation of transformation products. The chlorination treatment resulted in the most toxic transformation products according to an in-silico quantitative structure-activity relationship model. • Fentanyl was mostly resistant to hydrolysis, stable in environmental water matrices • Tertiary treatment produced transformation products in high abundance • Prolonged exposure to UV is required to transform fentanyl • Hypochlorite is an effective treatment for the rapid removal of fentanyl • In-silico model identified chlorination transformation products as highest concern