Detection of Δ9-tetrahydrocannabinol (THC) in hair using GC–MS

Detection of drugs from hair samples has become an imperative technique in forensic toxicological analysis. In this study, hair samples were collected from 20 cannabis users undergoing treatment at a rehabilitation center at different time intervals. Hair samples were cleaned and digested, followed by extraction and quantification of THC by GC–MS. At LOD of 0.1 ng/mg of THC, the concentration ranged from 0.16 to 2.3 ng/mg (mean, 0.95 ng/mg). Results indicate that THC is detectable after 3 months of last drug intake.