TESTING HUMAN HAIR FOR CANNABIS .2. IDENTIFICATION OF THC-COOH BY GC-MS-NCI AS A UNIQUE PROOF

To validate information on cannabis use, 11-nor-Delta 9-tetrahydrocann abinol-9-carboxylic (THC-COOH) was investigated in human hair. The ide ntification of THC-COOH in hair would document cannabis use more effec tively than the detection of the parent drug which might have come fro m environmental exposure in a smoky atmosphere. Samples (100 mg) were decontaminated with methylene chloride and destroyed by incubation in 1 mL of 1 N sodium hydroxide for 30 min at 95 degrees C in presence of 10 ng of THC-COOH-d(3). After cooling, samples were extracted by n-he xane/ethyl acetate after acidification with acetic acid. After derivat ization by PFPA-PFP-OH of the dry extract, drugs were separated on a H P1 capillary column, and detected by mass spectrometry (m/z 602) using negative chemical ionization with methane as reagent gas. Among 30 sa mples obtained from subjects deceased from fatal heroin overdose, 17 t ested positive for THC-COOH, in the range 0.02-0.39 ng/mg, with an ave rage of 0.12 ng/mg.