Citation

Zinka B, Epple S, Schick S, Skopp G, Graw M, Musshoff F. Drug Test. Anal. 2019; 11(2): 325-330.

Affiliation

Forensic Toxicological Centre GmbH, Bayerstr. 53, 80335, Munich, Germany.

Copyright

(Copyright © 2019, John Wiley and Sons)

DOI

10.1002/dta.2496

PMID

30193411

Abstract

A 100 μg/L or higher concentration of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) in blood serum is generally assumed to be associated with regular and/or heavy use of cannabis. At present, determination of the extent of cannabis use by means of the concentration of THC-COOH in hair has not been assessed. Therefore, we aimed at establishing a threshold for THC-COOH concentrations in hair to prove frequent consumption by comparing THC-COOH concentrations in 129 corresponding serum and hair samples, respectively. The concentration of THC-COOH in the serum was analysed by gas chromatography/mass spectrometry and in the hair by liquid chromatography/tandem mass spectrometry. Data were statistically evaluated using receiver operating characteristic curves and contingency tables. Our results suggest that a THC-COOH concentration of ≥ 4.2 pg/mg in hair was always accompanied by a THC-COOH concentration of at least 100 μg/L in blood serum. Should this be confirmed by further studies of a larger study population, a hair concentration of 4.2 pg/mg THC-COOH can be set as a threshold to predict regular and/or heavy consumption of cannabis even if no corresponding blood sample is available for analysis.

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Language: en

Keywords

11-nor-9-carboxy-Δ9-tetrahydrocannabinol; blood; frequent use; hair; threshold