Screening and Confirmation of Opioids, Amphetamines and Benzodiazepines in Wastewater by High-Resolution Mass Spectrometry

Assessing collective drug consumption based on the species and concentrations of illicit drugs and their metabolites in wastewater is an objective, real-time, accurate, convenient and effective monitoring technology. In order to establish a rapid screening and confirmation method for the abuse of opioids, amphetamines and benzodiazepines in wastewater, solid phase extraction was used to pretreat the wastewater sample, and ultra-high liquid chromatography tandem high resolution mass spectrometry was used to screen and confirm 36 kinds of analytes. Moreover, the method was applied to real wastewater samples collected from different wastewater treatment plants. Different HPLC columns and mobile phases were tested for optimization of the method. The peak shapes, retention time, separation and sensitivity of the chromatographic procedure were evaluated. Finally, an Accucore Hypersil Gold column (100 mm×2.1 mm×1.9 μm), and the mobile phases of ultrapure water with 2 mmol/L ammonium formate 0.1%-formic acid (A) and acetonitrile-methanol (1∶1, V/V) with 2 mmol/L ammonium formate and 0.1% formic acid were applied because of good peak shapes and separation. TraceFinder software was selected for rapid screening, and retention time, molecular mass, fragment ions and isotope distribution were collected as the screening basis. A substance could be judged as positive if it all met these 4 screening conditions. Therefore, the results obtained were more authentic and reliable. The LODs ranged from 5 to 20 ng/L. The extraction recoveries were higher than 70% for all compounds in wastewater, and the matrix effect ranged from -24.4% to 21.2%. In the real wastewater samples, 4 opioids of morphine, codeine, pethidine, tramadol, 1 amphetamine of methamphetamine and 4 benzodiazepines of diazepam, nordazepam, estazolam, alprazolam were detected, and the error of all compounds were less than 5×10-6. There are many kinds of abused substances in wastewater, and the regional prevalence is also different. The method established in this article can be used for rapid and accurate screening and confirmation abused substances in wastewater.