High-throughput bioanalytical method for analysis of synthetic cannabinoid metabolites in urine using salting-out sample preparation and LC–MS/MS

Abstract Herbal smoking mixtures which are sold as incense or potpourri and often referred to as ‘Spice’ are actually inactive plant matter adulterated with alkylamino indole based synthetic cannabinoids such as JWH-018 and JWH-073. Due to the inclusion of five synthetic cannabinoids, including JWH-018 and JWH-073, as Schedule I drugs by the Drug Enforcement Agency (DEA) in March 2011, it has become necessary for forensic laboratories to develop analytical methods to test for the presence of metabolites of synthetic cannabinoids. When a new analyte of interest emerges, most laboratories strive to develop a sample preparation procedure and validate an analytical method as quickly as possible and therefore, rely on effective but time consuming traditional protocols such as solid phase and liquid–liquid extraction. This research focuses on the examination of all aspects of sample preparation and analytical method development to streamline the analysis of four urinary metabolites of JWH-018 and JWH-073. A detailed evaluation of the β-glucuronide hydrolysis step lead to the reduction of time required for hydrolysis from 1 h at 50 °C to only 10 min at room temperature. By utilizing a salting-out assisted liquid–liquid extraction (SALLE) in place of traditional liquid–liquid extraction with a volatile solvent, processing time was saved and waste was reduced. The analysis run time was also shortened to one-third of a typical published run time by utilizing UPLC with isocratic conditions in place of conventional HPLC running a gradient method.