Traditional and emerging drugs of abuse in wastewater of Valencian Metropolitan Area (Spain)

Abstract

Illicit drugs are continuously discharged into wastewaters due to human excretion after their consumption, occasional direct disposal or clandestine laboratory wastes into sewage systems (Boles and Wells, 2010). Therefore, illicit drugs monitoring in waters and wastewaters can be useful because environmentalists manage and track environmental hazard of these substances and epidemiologists evaluate their nature, magnitude and consumption patterns. The main objective of this study was to optimize and validate an analytical procedure based on solid phase extraction (SPE) and liquid chromatography triple quadruple mass spectrometry (LC-QqQ-MS/MS), for the simultaneous analysis of 42 drugs of abuse and metabolites and to apply the validated procedure to influent and effluent wastewater samples collected from the wastewater treatment plants (WWTPs). In addition, back-calculation from the concentration of drugs of abuse in the influents of WWTPs provided an important tool for estimating its local consumption. Samples were collected at the WWTPs of Quart-Benager and Pinedo I and II. These plants treat most of the residual water from Valencia city and surronding villages. Sampling campaign was in March 2016 for seven consecutive days. Analysis of the target compounds was performed following a method based on solid phase extraction and liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS). The method detection limits ranged from 0.5 to 60 ng L-1 and the recoveries from 42 to 92 % for influents and from 61 to 101 % for effluents. The results from the concentration levels quantified in the influent and the effluent demonstrated that WWTPs eliminate these compounds in a high percentage with the exception of codeine. The most consumed drugs of abuse, according to the estimated concentrations of each compound as average value of the seven days were cocaine (907-1112 mg/day*1000 inhabitants) followed by ketamine (66-141 mg/day*1000 inhabitants), codeine (51-95 mg/day*1000 inhabitants), bufotenine (72-91 mg/day*1000 inhabitants), amphetamine (23-57 mg/day*1000 inhabitants), morphine (11-18 mg/day*1000 inhabitants), methadone (7.6-16 mg/day*1000 inhabitants), MDMA (7.7-13 mg/day*1000inhabitants), ethylamphetamine (3.6-5.0 mg/day*1000 inhabitants) and methamphetamine (2.1-2.9 mg/day*1000 inhabitants). The highest consumption of all drugs were detected in Pinedo I, that is the WWTP that treat only the urban sewage waters from Valencia city. In general the compsumption has undergone a decrease comparing with 2011-2013 campaigns.