Illicit drugs and their metabolites in urban wastewater: Analysis, occurrence and consumption in Xinjiang, China

The use of illicit drugs has increased considerably across the world. Wastewater-based epidemiology (WBE) of illicit drugs might help determine the types and quantity of illicit drugs consumed in a region. In this study, WBE was applied to analyze illicit drugs in five representative urban wastewater treatment plants (WWTPs) in Xinjiang, China. The collected samples were pretreated under optimized solid-phase extraction conditions and then analyzed using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The results revealed the presence of 9 of the 11 evaluated drugs; among them, the concentrations of these substances ranged as follows: METH (2.60-10.02 ng/L), MDMA (0.49-6.87 ng/L), MOR (4.53-44.75 ng/L), COD (2.24-8.30 ng/L), MTD (1.36-3.75 ng/L), COC (0.48 ng/L), THC (5.98-18.89 ng/L), BE (1.12-2.45 ng/L) and KET (1.50 ng/L). And an estimate of the per capita consumption revealed morphine (10.2 mg/d/1000inhabitants), cannabis (3.9 mg/d/1000inhabitants), 3,4-methylenedioxymethamphetamine (3.9 mg/d/1000 inhabitants), and methamphetamine (2.2 mg/d/1000 inhabitants) as the main substances of abuse in Xinjiang, China. The results of this study might be taken as a reference for future studies on the continuous monitoring of such drugs.