Determination of cannabinoids in hair Indicators for illegal vs CBD-rich cannabis use.
Cannabis products rich in cannabidiol (CBD) and low in Δ9-tetrahydrocannabinol (THC) (e.g., light cannabis in Italy) are becoming widely popular and available on the market as replacements for THC preparations and tobacco for their recreational andor therapeutic benefits. In this paper, which aims to establish alternative discrimination parameters between hair samples from CBD-rich and THC-prevalent cannabis users, cannabinoid concentrations, such as THC, CBD, 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) and 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) were quantified in 127 hair samples by a GC-MSMS technique. Initially, this analysis was able to discriminate two cohorts cohort 1 (individuals with THC values ≥ 0.05 ngmg and THC-COOH ≥ 0.2 pgmg or THC-positive users, n 60) and cohort 2 (individuals with THC values ranging between 0.01 and 0.05 ngmg and THC-COOH or 11-OH-THC ≥ LOQs, n 67). The evaluation of CBDTHC ratio in cohort 2 identified two further sub-cohorts 2a (CBDTHC<<1 or 1, THC-prevalent cannabis users) and 2b (CBDTHC>>1, suspected CBD-rich and THC-low cannabis users). The latter showed unusual profiles for THC metabolites, in particular for 11-OH-THC. Statistical evaluation of the data of cohort 1, cohort 2a and cohort 2b yielded significant differences in CBDTHC and THC11-OH-THC. Based on the analysis of 337 seized cannabis samples and 630 CBD-richlight cannabis samples by GC-FID and GC-MS, respectively, we also evaluated statistical differences in the CBDTHC ratio between biological (hair) and plant-derived samples. Considering the legal implications of a positive result, the obtained findings could be relevant for the interpretation of cannabinoid concentrations in hair. Further studies are necessary to elucidate the reason behind the unusual metabolic ratios.