[Optimization and Validation of the Analytical Method to Detect Common Illicit Drugs in Wastewater]

Illicit drugs have been recognized as a group of emerging pollutants.Based on previous research,procedures to pre-treat wastewater including SPE column,pH of water samples,and processes of washing,acidifying and re-dissolving were compared.It was found that the best recovery was achieved when wastewater was adjusted to pH=2 and Oasis MCX column was used.It was not necessary to flush the loaded column or to acidify the eluate prior to evaporation using nitrogen steam.After evaporation,it is recommended to redissolve the evaporated samples using 200 μL acetonitrile and 100 μL acetonitrile+100 μL 5 mmol·L^-1 ammonium acetate in Milli-Q water for HILIC-UPLC-MS/MS and C18-UPLC-MS/MS,respectively.After comparing retention times,limit of detection,limit of quantification,recoveries,and matrix effects of HILIC and C18 methods,C18-UPLC-MS/MS was chosen.Influent and effluent samples from 12 wastewater treatment plants in Beijing were analyzed using the optimized method for validation.The validated methods set a firm foundation to apply the sewage-based epidemiology to monitor illicit drug abuse in China.