Determination of four cannabinoids in wastewater based on a hyperbranched mixed-mode anion exchange magnetic solid-phase extraction adsorbent combined with UHPLC-MS/MS

Cannabis is the most frequently abused drug worldwide, and the number of cannabis users is still growing. The high lipophilicity of cannabinoids results in extremely low concentrations in wastewater, which poses difficulties and challenges for monitoring cannabinoids. In this study, a hyperbranched mixed-mode anion exchange magnetic adsorbent Fe 3 O 4 @poly(GMA/DVB-WAX) was designed based on the structural characteristics of cannabinoids, which was prepared through copolymerization of glycidyl methacrylate (GMA) and divinylbenzene (DVB) on the surface of oleic acid coated Fe 3 O 4 microspheres followed by hyperbranched modification with ethylenediamine (EDA) and 1,4-butanediol glycidyl ether (BDDGE). This magnetic solid-phase extraction (MSPE) adsorbent can selectively extract four cannabinoids, Δ 9 -tetrahydrocannabinol (THC), cannabidiol (CBD), cannabinol (CBN), 11-nor-9-carboxy-Δ 9 -tetrahydrocannabinol (THC-COOH), from wastewater through the synergistic effects of hydrophobic interactions, electrostatic interactions, π-π stacking interactions, and hydrogen bonding interactions. The entire extraction time of the adsorbent only takes five minutes and the extraction recovery rates were in the range of 69.4 %-94.0 % for four cannabinoids after the MSPE procedure optimization. An MSPE-UHPLC-MS/MS quantitative method for determination of four cannabinoids in wastewater was established and validated. The results showed that this method had a good linearity within the range of 0.5–100 ng/L (r 2  > 0.9962). The limits of detection and the limits of quantification were 0.17–0.33 ng/L and 0.50–1.00 ng/L, respectively. The proposed MSPE-UHPLC-MS/MS method based on Fe 3 O 4 @poly(GMA/DVB-WAX) is a convenient, sensitive and reliable strategy and has great application prospects in the analysis of trace cannabinoids in wastewater.