A comparative study on the concentrations of 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THCCOOH) in head and pubic hair

Abstract

In this study, the concentrations of 11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THCCOOH) in pubic, axillary and beard hair were measured and the correlation between the concentrations of THCCOOH in head and pubic hair from same cannabis users were evaluated. The papers on body hair analysis for THCCOOH were rarely found although police officers submit body hair as a complimentary specimen to forensic laboratories in case cannabis users had no hair. Head, pubic, axillary, and beard hair were collected. All hair samples were cut into 0.5mm segments and decontaminated with methanol, digested with 1 mL of 1M NaOH at 85 °C for 30 min and extracted in 2 mL of n-hexane:ethyl acetate (9:1) two times after adding 1 mL of 0.1N sodium acetate buffer (pH = 4.5) and 200 μL of acetic acid followed by derivatization with 50 μL of PFPA and 25 μL of PFPOH for 30 min at 70 °C. The extracts were analyzed using gas chromatography tandem mass spectrometry operating in negative chemical ionization mode (GC/MS/MS-NCI). We determined the concentrations of THCCOOH in both pubic and head hair. The concentrations of THCCOOH in pubic hair were higher than those in head hair. We also evaluated the concentrations of THCCOOH in body hair (pubic, axillary and beard hair) and head hair according to the positive/negative urine test results. There was no statistically significant difference in the concentrations of THCCOOH in head and body hair according to urine results.