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Hair analysis for Delta9-tetrahydrocannabinolic acid A--new insights into the mechanism of drug incorporation of cannabinoids into hair.
Forensic Sci Int. 2010 Mar 20; 196(1-3):10-3.FS

Abstract

Differentiation between external contamination and incorporation of drugs or their metabolites from inside the body via blood, sweat or sebum is a general issue in hair analysis and of high concern when interpreting analytical results. In hair analysis for cannabinoids the most common target is Delta9-tetrahydrocannabinol (THC), sometimes cannabidiol (CBD) and cannabinol (CBN) are determined additionally. After repeated external contamination by cannabis smoke these analytes are known to be found in hair even after performing multiple washing steps. A widely accepted strategy to unequivocally prove active cannabis consumption is the analysis of hair extracts for the oxidative metabolite 11-nor-9-carboxy-THC (THC-COOH). Although the acidic nature of this metabolite suggests a lower rate of incorporation into the hair matrix compared to THC, it is not fully understood up to now why hair concentrations of THC-COOH are generally found to be much lower (mostly <10 pg/mg) than the corresponding THC concentrations. Delta9-Tetrahydrocannabinolic acid A (THCA A) is the preliminary end product of the THC biosynthesis in the cannabis plant. Unlike THC it is non-psychoactive and can be regarded as a 'precursor' of THC being largely decarboxylated when heated or smoked. The presented work shows for the first time that THCA A is not only detectable in blood and urine of cannabis consumers but also in THC positive hair samples. A pilot experiment performed within this study showed that after oral intake of THCA A on a regular basis no relevant incorporation into hair occurred. It can be concluded that THCA A in hair almost exclusively derives from external contamination e.g. by side stream smoke. Elevated temperatures during the analytical procedure, particularly under alkaline conditions, can lead to decarboxylation of THCA A and accordingly increase THC concentrations in hair. Additionally, it has to be kept in mind that in hair samples tested positive for THCA A at least a part of the 'non-artefact' THC probably derives from external contamination as well, because in condensate of cannabis smoke both THC and THCA A are present in relevant amounts. External contamination by side stream smoke could therefore explain the great differences in THC and THC-COOH hair concentrations commonly found in cannabis users.

Authors+Show Affiliations

Institute of Forensic Medicine, University Medical Centre Freiburg, Freiburg, Germany. volker.auwaerter@uniklinik-freiburg.deNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

20129747

Citation

Auwärter, Volker, et al. "Hair Analysis for Delta9-tetrahydrocannabinolic Acid A--new Insights Into the Mechanism of Drug Incorporation of Cannabinoids Into Hair." Forensic Science International, vol. 196, no. 1-3, 2010, pp. 10-3.
Auwärter V, Wohlfarth A, Traber J, et al. Hair analysis for Delta9-tetrahydrocannabinolic acid A--new insights into the mechanism of drug incorporation of cannabinoids into hair. Forensic Sci Int. 2010;196(1-3):10-3.
Auwärter, V., Wohlfarth, A., Traber, J., Thieme, D., & Weinmann, W. (2010). Hair analysis for Delta9-tetrahydrocannabinolic acid A--new insights into the mechanism of drug incorporation of cannabinoids into hair. Forensic Science International, 196(1-3), 10-3. https://doi.org/10.1016/j.forsciint.2009.12.023
Auwärter V, et al. Hair Analysis for Delta9-tetrahydrocannabinolic Acid A--new Insights Into the Mechanism of Drug Incorporation of Cannabinoids Into Hair. Forensic Sci Int. 2010 Mar 20;196(1-3):10-3. PubMed PMID: 20129747.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Hair analysis for Delta9-tetrahydrocannabinolic acid A--new insights into the mechanism of drug incorporation of cannabinoids into hair. AU - Auwärter,Volker, AU - Wohlfarth,Ariane, AU - Traber,Jessica, AU - Thieme,Detlef, AU - Weinmann,Wolfgang, Y1 - 2010/02/02/ PY - 2009/07/30/received PY - 2009/08/31/accepted PY - 2010/2/5/entrez PY - 2010/2/5/pubmed PY - 2010/6/11/medline SP - 10 EP - 3 JF - Forensic science international JO - Forensic Sci Int VL - 196 IS - 1-3 N2 - Differentiation between external contamination and incorporation of drugs or their metabolites from inside the body via blood, sweat or sebum is a general issue in hair analysis and of high concern when interpreting analytical results. In hair analysis for cannabinoids the most common target is Delta9-tetrahydrocannabinol (THC), sometimes cannabidiol (CBD) and cannabinol (CBN) are determined additionally. After repeated external contamination by cannabis smoke these analytes are known to be found in hair even after performing multiple washing steps. A widely accepted strategy to unequivocally prove active cannabis consumption is the analysis of hair extracts for the oxidative metabolite 11-nor-9-carboxy-THC (THC-COOH). Although the acidic nature of this metabolite suggests a lower rate of incorporation into the hair matrix compared to THC, it is not fully understood up to now why hair concentrations of THC-COOH are generally found to be much lower (mostly <10 pg/mg) than the corresponding THC concentrations. Delta9-Tetrahydrocannabinolic acid A (THCA A) is the preliminary end product of the THC biosynthesis in the cannabis plant. Unlike THC it is non-psychoactive and can be regarded as a 'precursor' of THC being largely decarboxylated when heated or smoked. The presented work shows for the first time that THCA A is not only detectable in blood and urine of cannabis consumers but also in THC positive hair samples. A pilot experiment performed within this study showed that after oral intake of THCA A on a regular basis no relevant incorporation into hair occurred. It can be concluded that THCA A in hair almost exclusively derives from external contamination e.g. by side stream smoke. Elevated temperatures during the analytical procedure, particularly under alkaline conditions, can lead to decarboxylation of THCA A and accordingly increase THC concentrations in hair. Additionally, it has to be kept in mind that in hair samples tested positive for THCA A at least a part of the 'non-artefact' THC probably derives from external contamination as well, because in condensate of cannabis smoke both THC and THCA A are present in relevant amounts. External contamination by side stream smoke could therefore explain the great differences in THC and THC-COOH hair concentrations commonly found in cannabis users. SN - 1872-6283 UR - https://www.unboundmedicine.com/medline/citation/20129747/Hair_analysis_for_Delta9_tetrahydrocannabinolic_acid_A__new_insights_into_the_mechanism_of_drug_incorporation_of_cannabinoids_into_hair_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0379-0738(09)00524-6 DB - PRIME DP - Unbound Medicine ER -