Testing Human Hair for Cannabis. II. Identification of THC-COOH by GC-MS-NCI as a Unique Proof

J Forensic Sci. 1995 Jul;40(4):619-22.


To validate information on cannabis use, 11-nor-delta 9-tetrahydrocannabinol-9-carboxylic (THC-COOH) was investigated in human hair. The identification of THC-COOH in hair would document cannabis use more effectively than the detection of the parent drug which might have come from 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-d3. After cooling, samples were extracted by n-hexane/ethyl acetate after acidification with acetic acid. After derivatization by PFPA-PFP-OH of the dry extract, drugs were separated on a HP1 capillary column, and detected by mass spectrometry (m/z 602) using negative chemical ionization with methane as reagent gas. Among 30 samples obtained from subjects deceased from fatal heroin overdose, 17 tested positive for THC-COOH, in the range 0.02-0.39 ng/mg, with an average of 0.12 ng/mg.

MeSH terms

  • Adult
  • Dronabinol / analogs & derivatives*
  • Dronabinol / analysis
  • Gas Chromatography-Mass Spectrometry / methods*
  • Hair / chemistry*
  • Humans
  • Marijuana Abuse*


  • 11-nor-delta(9)-tetrahydrocannabinol-9-carboxylic acid
  • Dronabinol