Determination of cannabinoids in urine, oral fluid and hair samples after repeated intake of CBD-rich cannabis by smoking

Cannabidiol prevalent (CBD-rich) cannabis derivatives are increasingly popular and widely available on the market as replacement of THC, tobacco substitutes or therapeutics for various health conditions. In this paper, we evaluate the impact of a repeated CBD-rich cannabis intake on levels of cannabinoids in biological samples. Urine, oral fluid and hair (pubic and head) samples were obtained from a naive user during a 26-day smoking period of one 250-mg CBD-rich cannabis joint/day containing 6.0% cannabidiol (CBD; 15 mg) and 0.2% delta-9-tetrahydrocannabinol (THC; 0.5 mg). In total, 35 urine, 8 oral fluid and 4 hair sample were collected. Cannabinoids concentrations were quantified by a UHPLC/MSn technique. The results suggested that the repeated exposure to CBD-rich cannabis (containing small amounts of THC) can generate positive results in biological samples. Urinary concentrations of 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC–COOH) were quantitatively detected after 8 days from the smoking start and exceeded the 15 ng/mL cut-off limit on day-15 even in the urine sample collected 12 h after the last intake. In the oral fluid collected on day-26, no cannabinoids were found before the cannabis intake, thus excluding accumulation, while THC was detectable up to 3 h after the cannabis intake, at concentrations progressively decreasing from about 18 to 6 ng/mL. Hair samples collected one week after the end of the study turned out negative for THC and THC–COOH, suggesting that this matrix is suitable to discriminate the chronic consumption of CBD-rich cannabis from THC-prevalent products. The obtained findings are relevant for the interpretations of cannabinoids levels in biological fluids, also in light of the legal implications of a positive result.