Detection of JWH-018 and JWH-073 by UPLC-MS-MS in postmortem whole blood casework

Synthetic cannabinoids have been detected in various herbal blends sold legally in convenience stores, smoke shops, and on the Internet. Many of these compounds have extreme forensic significance. We developed and validated a rapid ultra-performance liquid chromatography-tandem mass spectrometry method for the determination of trace concentrations of two of these compounds, JWH-018 and JWH-073, in human blood. Samples underwent liquid-liquid extraction at pH 10.2 into ethyl ether. Tandem mass spectrometry was performed in positive electrospray ionization mode with multiple reaction monitoring using two transitions and one calculated ion transition ratio for each analyte. Deuterated analogs were used as internal standards. Total run time was 2.6 min. The linear dynamic range was 0.05-50 ng/mL with a limit of detection of 0.01 ng/mL for each analyte. Intra-run imprecision (at two different concentration levels, 2 and 8 ng/mL) was 3.9-10.3% for JWH-018 and 3.5-6.2% for JWH-073. Inter-run imprecision was 6.5-7.2% for JWH-018 and 4.8-5.5% for JWH-073. Intra-run accuracy was 95.9-112.7% for JWH-018 and 92.6-104.7% for JWH-073. Inter-run accuracy was 99.1-107.0% for JWH-018 and 97.7-102.0% for JWH-073. Carryover, exogenous drug interferences, ion suppression and matrix selectivity were also assessed. The method has been applied to postmortem forensic casework received by the laboratory and has proven to be robust and reliable. Concentrations of authentic samples have ranged from 0.1-199 ng/mL for JWH-018 and 0.1-68.3 ng/mL for JWH-073.