Presence of the ketamine analog of 2-fluorodeschloroketamine residues in wastewater.

Ketamine (KET) analogs are increasingly emerging as new psychoactive substances (NPS). The present report describes the first detection of the KET analog, 2-fluorodeschloroketamine (2F-DCK), in influent samples collected from nine wastewater treatment plants in seven major Chinese cities from 2018 to 2020 by wastewater-based epidemiology (WBE). An analytical method based on solid-phase extraction and subsequent gas chromatography-mass spectrometry was developed for the detection of 2F-DCK and KET. The stability experiments showed that 2F-DCK and KET remained stable in wastewater for 15 days at room and frozen temperatures, and at two pH values (pH = 7 and pH = 2), with residue amounts between 90% and 110%. KET was detected in all samples, whereas 2F-DCK was detected in only four samples: from Guangzhou in 2018, Shenzhen in 2019, and Quanzhou and Nanning in 2020, indicating that 2F-DCK has been used as early as 2018 in China. The renal clearance of 2F-DCK was predicted based on the quantitative structure-pharmacokinetic relationship model, which was used to calculate an excretion factor of 3.7. The 2F-DCK consumption in four cities ranged from 3.71 ± 0.05 to 55 ± 0.09 mg/day/1000 inh, and KET ranged from 1.3 ± 0.04 to 76.5 ± 4.63 mg/day/1000 inh. This is the first study to investigate 2F-DCK by WBE, which provides relevant real-time data on the growth of NPS use, as well as useful information for the government to develop new policies.