Detecting synthetic cannabinoids, THC and THC-COOH in wastewater Online-SPE-UPLC-MS/MS method

In this study, an on-line solid phase extraction - Ultra High liquid phase - tandem mass spectrometry (Online-SPE-UPLC-MS/MS) detection method was established to simultaneously detect the 9 analytes in domestic wastewater, including 7 synthetic cannabinoids, Δ9-tetrahydrocannabinol (THC) and 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH). After the analyzed samples pH was adjusted to 7 by adding to the internal standard solution and then filtered with 0.2 μm filter membrane, the analytes in the sample were extracted online using solid phase extraction. The analytes were loaded into the column at the flow rate of 0.4mL/min, and the column temperature was 40 ℃. Using 0.1% formic acid-acetonitrile as mobile phase elution, qualitative and quantitative analysis was performed in ESI positive ion scanning and multiple reaction monitoring (MRM) mode. The method was fully validated the THC and THC-COOH linear ranges were 5—250 ng·L−1, and the other analytes linear ranges were 1—250 ng·L−1(R2>0.998), the intra-day precision was from 1.29% to 10.3%, and inter-day precision was from 1.91% to 17.5%, except for 4F-MDMB-BUTICA, others the recoveries ranged from 85.2% to 115%. The storage time of 9 analytes at different temperatures was discussed. As a result, 4F-MDMB-BUTICA and THC had good stability at room temperature, and the other 7 analytes had good stability at 4 ℃ and -20 ℃. The Online-SPE-UPLC-MS/MS method can simultaneously detect 7 kinds of synthetic cannabinoids, THC and THC-COOH in wastewater within 12 minutes, which has been successfully applied to urban wastewater monitoring in China.