Proof of active cannabis use comparing 11‐hydroxy‐∆9‐tetrahydrocannabinol with 11‐nor‐9‐carboxy‐tetrahydrocannabinol concentrations

Abstract

Testing hair for cannabis use has increasingly been scrutinised due to exposure to second-hand smoke or environmental contamination. Confirmation of drug use involving detection of metabolites such as 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH) and 11-hydroxy-delta-9-tetrahydrocannabinol (THC-OH) having very rarely been considered. We developed a new, simplified procedure with regard to expenditure of time and material to determine delta-9-tetrahydrocannabinol (THC, qualitatively), as well as THC-OH and THC-COOH (quantitatively) from 587 hair samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) which was compared to hitherto established methods (n = 3). Compared to conventional methanolic extraction alkaline dissolution resulted in higher concentrations for THC-OH. Concentrations determined from specimens ranged from 0.01 to 18.7 ng THC/mg hair, 0.05-37.6 pg THC-OH/mg hair, and from 0.1 to 54.3 pg THC-COOH/mg hair. THC was detectable in 70.4% samples along with both metabolites from more than half of these samples. In 12.9% of THC-positive cases, neither THC-OH nor THC-COOH were present. In 8.9% of THC-negative cases, it was possible to detect metabolites either alone or in combination. THC-OH could more frequently be detected than THC-COOH and appeared to be less susceptible to cosmetic treatment. In summary, THC-OH turned out to be a further suitable marker to prove cannabis use. Determination of both metabolites is recommended to unequivocally differentiate consumption from external exposure or contamination.

Simultaneous quantification of THC‐COOH, OH‐THC, and further cannabinoids in human hair by gas chromatography–tandem mass spectrometry with electron ionization applying automated sample preparation

“…The method, which is presented in this work, is a contribution to the current trend in the quantitation of OH‐THC in human hair (which is considered to be a suitable marker in addition to THC‐COOH), to differentiate between consumption and contamination …”

“…Quantification of the phase I THC‐metabolite OH‐THC in hair is a subject of interest due to its ambivalent characteristic as an active metabolite with biological effects. It could be a valuable additional consumption marker but has, thus far, seldom been investigated in hair analysis …”

“…It could be a valuable additional consumption marker but has, thus far, seldom been investigated in hair analysis. [22][23][24][25] Furthermore, the phase I metabolites (THC-COOH, OH-THC) undergo phase II biotransformation with glucuronic acid in vivo, forming corresponding glucuronides. 26 Thus, THC-COOH-glucuronide has been already characterized in hair.…”

Can a threshold for 11‐nor‐9‐carboxy‐Δ9 ‐tetrahydrocannabinol in hair be derived when its respective concentration in blood serum indicates regular use?

“…As the latest scientific studies suggest, more reliable statements to prove cannabis use may also include the detection of THC‐COOH in hair samples . Because THC‐COOH is only generated as a metabolic product of THC within the body of the user and is not present in cannabis smoke, it is accepted as a reliable proof of active consumption.…”

“…3 The results of our study strongly suggest that a THC-COOH As the latest scientific studies suggest, more reliable statements to prove cannabis use may also include the detection of THC-COOH in hair samples. 16 Because THC-COOH is only generated as a meta- Nonetheless the combined determination of THC-COOH in both blood serum and hair seems to be a more appropriate method to identify heavy users of cannabinoids than the isolated viewing.…”