Assessment of norfloxacin degradation induced by plasma-produced ozone using surface-enhanced Raman spectroscopy Qing Huang a, b, * , Cao Fang a, c , Muhammad Muhammad a, b , Guohua Yao a a Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Institute of Technical Biology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, China b University of Science & Technology of China, Hefei, 230026, China c Anhui Jianzhu University, Hefei, 230601, China highlights graphical abstract  A special DBD plasma instrument was employed to produce ozone to treat norfloxacin.  A novel approach of SERS was applied to analyze the degradation products.  The degradation pathways/mecha- nisms were elucidated using SERS and HPLC-MS.  Defluorination of norfloxacin by ozone was proved the main degra- dation pathway. article info Article history: Received 15 July 2019 Received in revised form 16 August 2019 Accepted 18 August 2019 Available online 19 August 2019 Handling Editor: Yongmei Li Keywords: Norfloxacin Degradation Surface-enhanced Raman spectroscopy (SERS) Low-temperature plasma Ozone Density function theory (DFT) abstract In this work, we employed surface-enhanced Raman spectroscopy (SERS) combined with density functional theory (DFT) calculation to investigate the pathways/mechanisms of the norfloxacin degra- dation by oxygen plasma produced ozone. The main degradation products were analyzed by the spec- troscopic method, which revealed the breakage of the CeF bond and fracture of piperazinyl and quinolone moieties. In particular, we showed that the main degradation pathway was defluorination of norfloxacin, and this process could be quantitatively assessed by our proposed SERS approach. © 2019 Published by Elsevier Ltd. 1. Introduction Norfloxacin is an antibiotic drug commonly used in human and animal medicine (Cao et al., 2018). Nowadays plenty of antibiotics including norfloxacin are either intentionally or carelessly released to natural water environment, posing potential threats to human * Corresponding author. Key Laboratory of High Magnetic Field and Ion Beam Physical Biology, Institute of Technical Biology and Agriculture Engineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, Hefei, 230031, China. E-mail address: huangq@ipp.ac.cn (Q. Huang). Contents lists available at ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere https://doi.org/10.1016/j.chemosphere.2019.124618 0045-6535/© 2019 Published by Elsevier Ltd. Chemosphere 238 (2020) 124618