Detection of synthetic cannabinoids in oral fluid using ELISA and LC-MS-MS

Synthetic cannabinoids are often referred to as 'Spice' or K2 compounds. Detection of these compounds in oral fluid has, to date, been limited to chromatographic procedures such as liquid chromatography with tandem mass spectrometry detection. We report the first analytical immunoassay for the screening of some synthetic cannabinoids in oral fluid specimens collected with the Quantisal™ device. JWH-200 was chosen as the calibration standard, because parent compounds, not metabolites, are predominantly detected in oral fluid. The immunoassay is capable of detecting JWH-200, JWH-018, JWH-073, JWH-022, AM-2201, AM-2232 and AM-1220. The assay was validated according to accepted laboratory protocols and applied to 32 authentic oral fluid specimens previously analyzed using LC-MS-MS at an accredited laboratory. The assay is sensitive, with a cutoff concentration of 0.25 ng/mL, and has a wide working range from 0.1 to 5 ng/mL. Intra- and interday precision were determined to be <10%. The screening method was completely validated and characterized; critical aspects of the screening included the incorporation of a preincubation step that improves the sensitivity of the assay to allow relevant concentrations of synthetic compounds in oral fluid to be detected.