Simultaneous determination of 38 indazole amides synthetic cannabinoids and 15 metabolites in wastewater by solid phase extraction-liquid chromatography-tandem mass spectrometry

Synthetic cannabinoids （SCs）， which are significantly more potent and efficacious than natural cannabis， are among the most widely abused new psychoactive substances. The emergence of the so-called first-generation SCs was followed by other SCs that eventually led to the development of eighth-generation indole/indazole amide-based SCs. Indeed， this entire category of SCs was added to the list of controlled substances on July 1， 2021. SCs can be disguised in various ways and are commonly sold in the form of electronic cigarette oil. SCs quickly enter the bloodstream through the lungs when smoked and are eventually excreted in the forms of precursors and metabolites in urine and feces following oxidation and metabolism， and finally enter the urban sewage system. SCs abuse can be studied and evaluated by analyzing SCs and their metabolites in municipal wastewater， thereby providing a practical reference. Therefore， methods for detecting SCs and their metabolites in wastewater need to be developed.In this study， a solid phase extraction （SPE）-liquid chromatography-tandem mass spectrometry （LC-MS/MS） method was developed for the simultaneous determination of 38 indazole amide SCs and 15 metabolites in wastewater. Samples were treated using Oasis^Ⓡ MCX SPE， and multiple reaction monitoring （MRM） mode was used with mobile phases comprising （A） 0.1% formic acid aqueous solution and （B） methanol-acetonitrile （1∶1， v/v）. The following gradient-elution conditions were used： 0-8 min， 55%A-15%A； 8-15 min， 15%A； 15-16 min， 15%A-55%A； 16-18 min， 55%A. Target analytes were separated using a SHIMADZU Shim-pack GIST-HP C18 AQ column （100 mm×2.1 mm， 1.9 µm） at a column temperature of 40 ℃ and a flow rate of 0.4 mL/min. The injection volume was 10 µL. The 38 SCs and 15 metabolites were identified within 11 min using MRM mode； these analytes exhibited good linear relationships and correlation coefficients （<i>r</i>） exceeding 0.990 5. The limits of detection were 0.03-1.30 ng/L， and the limits of quantification were 0.11-4.30 ng/L， respectively， which meet the requirements for analyzing SCs and their metabolites in actual samples. Precisions （<i>n</i>=6） were determined to be 2.1%-15.5% by spiking wastewater samples with 10， 50， and 200 ng/L of the 38 SCs and 15 metabolites. Recoveries of the 38 SCs and 15 metabolites were 61.2%-129.3% by spiking wastewater samples at low （10 ng/L）， medium （50 ng/L）， and high （200 ng/L） levels. Good performance was observed when real samples were analyzed. The developed method is accurate， rapid， sensitive， and effective for the determination of the 38 SCs and 15 metabolites in wastewater， thereby satisfying monitoring and evaluation requirements.