TESTING HUMAN HAIR FOR CANNABIS

To validate information on cannabis use, we investigated human hair an d pubic hair for cannabinoids (THC and THC-COOH) by gas chromatography /mass spectrometry. Samples (100 mg approximately) were decontaminated with methylene chloride, then pulverized and dissolved in 1 ml 1 N Na OH for 10 min at 95 degrees C in the presence of 200 ng of deuterated standards. After cooling, samples were extracted by n-hexane/ethyl ace tate after acidification with acetic acid. After derivatization of the dry extract by PFPA/PFP-OH, the drugs were separated on a 30-m capill ary column and detected using selected-ion monitoring (m/z 377 and 459 for THC and THC-COOH, respectively). Forty-three hair samples were ob tained from fatal heroin overdose cases. Among them, 35% tested positi ve for cannabinoids. Hair concentrations ranged from 0.26 to 2.17 ng/m g (mean, 0.74 ng/mg) and 0.07 to 0.33 ng/mg (mean, 0.16 ng/mg) of THC and THC-COOH, respectively. As is generally the case for other drugs d etected in hair, metabolite concentration was always lower when compar ed to the parent drug concentration. In pubic hair, THC concentrations ranged from 0.34 to 3.91 ng/mg (mean, 1.35 ng/mg) and THC-COOH concen trations from 0.07 to 0.83 ng/mg (mean, 0.28 ng/mg). In most cases, th e highest cannabinoid concentration was found in pubic hair, suggestin g that this sample may be the more suitable for cannabis testing.