Determination of cannabinoids in hair: Indicators for illegal vs CBD-rich cannabis use

Cannabis products rich in cannabidiol (CBD) and low in Delta 9-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 and/or 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-Delta 9-tetrahydrocannabinol (THC-COOH) and 11-hydroxy-Delta 9-tetrahydrocannabinol (11-OH-THC) were quantified in 127 hair samples by a GC-MS/MS technique. Initially, this analysis was able to discriminate two cohorts: cohort 1 (individuals with THC values = 0.05 ng/mg and THC-COOH >= 0.2 pg/mg or THC-positive users, n = 60) and cohort 2 (individuals with THC values ranging between 0.01 and 0.05 ng/mg and THC-COOH or 11-OH-THC >= LOQs, n = 67). The evaluation of CBD/THC ratio in cohort 2 identified two further sub-cohorts 2a (CBD/THC < < 1 or similar to 1, THC-prevalent cannabis users) and 2b (CBD/THC > > 1, suspected CBD-rich and THC-low cannabis users). The latter showed unusual profiles for THC meta-bolites, in particular for 11-OH-THC. Statistical evaluation of the data of cohort 1, cohort 2a and cohort 2b yielded significant differences in CBD/THC and THC/11-OH-THC. Based on the analysis of 337 seized cannabis samples and 630 CBD-rich/light cannabis samples by GC-FID and GC-MS, respectively, we also evaluated statistical differences in the CBD/THC 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. (C) 2022 Published by Elsevier B.V.

Automated summary

Cannabis products with high levels of CBD and low levels of THC are increasingly popular as alternatives to THC preparations and tobacco. This study aimed to establish parameters for distinguishing between hair samples from CBD-rich and THC-prevalent cannabis users. The analysis of 127 hair samples revealed significant differences in cannabinoid concentrations between different cohorts, and further studies are needed to understand the unusual metabolic ratios.