Determination of cannabinoid and synthetic cannabinoid metabolites in wastewater by liquid–liquid extraction and ultra‐high performance supercritical fluid chromatography‐tandem mass spectrometry

For the first time, ultra‐high performance supercritical fluid chromatography (UHPSFC) coupled to tandem mass spectrometry has been used to determine cannabinoid and synthetic cannabinoid residues in wastewater. Combined with a downscaled version of the classic liquid‐liquid extraction, the proposed method allows for the quantification of Δ9‐tetrahydrocannabinol, three of its major metabolites (the monohydroxylated, the dehydroxylated, and the carboxylated species) and four synthetic cannabinoid metabolites (from the JWH‐series) at low ng L−1 levels. Limits of quantification are in the 1–59 ng L−1 range, with recovery between 62 and 122% in ultrapure water and between 59 and 138% in wastewater. The applicability of the developed methodology was confirmed by the analysis of real wastewater, where cannabis metabolites could be positively quantified in all the samples analyzed. It is, therefore, a fast and simple alternative to common solid‐phase extraction‐liquid chromatography‐mass spectrometry procedures for the determination of these low polar substances in water.