Pressurized liquid extraction for the determination of cannabinoids and metabolites in hair: Detection of cut-off values by high performance liquid chromatography-high resolution tandem mass spectrometry

tHair analysis has become a routine procedure in most forensic laboratories since this alternative matrixpresents clear advantages over classical matrices; particularly wider time window, non-invasive samp-ling and good stability of the analytes over time. There are, however, some major challenges for theanalysis of cannabinoids in hair, mainly related to the low concentrations of 11-nor-9-carboxy-9-tetrahydrocannabinol (THC-COOH), that is the major metabolite. In this study a fast, accurate and sensitivemethod for the determination of cannabinol, cannabidiol, THC and THC-COOH in hair has been devel-oped. The extraction of analytes from hair (50 mg) is based on an automated pressurized liquid extraction(PLE) using water modified with the surfactant sodium dodecyl sulphate as eluent phase. PLE extract isthen cleaned up by SPE using polymeric reversed phase cartridges Strata XL before the injection in theHPLC–HRMS/MS system. Chromatographic conditions obtained with a fused-core column allowed a goodseparation of the analytes in less than 4 min. The whole procedure has been validated according to SWG-TOX guidelines. The LLOQs obtained for THC-COOH and the other analytes were respectively 0.1 and2 pg/mg. To the best of our knowledge, this is the first LC–MS/MS based method that allows the detectionof THC-COOH in hair at values lower than the cut-off.