title: Determination of Δ9-tetrahydrocannabinolic acid A (Δ9-THCA-A) in whole blood and plasma by LC-MS/MS and application in authentic samples from drivers suspected of driving under the influence of cannabis.
abstract: Delta-9-tetrahydrocannabinolic acid A (THCA-A) is the biosynthetic precursor of delta-9-tetrahydrocannabinol (THC) in cannabis plants, and has no psychotropic effects. THCA-A can be detected in blood and urine, and several metabolites have been identified. THCA-A was also shown to be incorporated in hair by side stream smoke to a minor extent, but incorporation via blood stream or sweat seems unlikely. The detection of THCA-A in biological fluids may serve as a marker for differentiating between the intake of prescribed THC medication - containing only pure THC - and cannabis products containing THC besides THC-acid A and other cannabinoids. However, the knowledge about its usefulness in forensic cases is very limited. The aim of the present work was the development of a reliable method for THCA-A determination in human blood or plasma using LC-MS/MS and application to cases of driving under the influence of drugs. Fifty eight (58) authentic whole blood and the respective plasma samples were collected from drivers suspected of driving under the influence of cannabis from the region of Bern (Switzerland). Samples were first tested for THC, 11-OH-THC and THC-COOH, and then additionally for THCA-A. For this purpose, the existing LC-MS/MS method was modified and validated, and found to be selective and linear over a range of 1.0 to 200ng/mL (the correlation coefficients were above 0.9980 in all validation runs). Limit of detection (LOD) and limit of quantification (LOQ) were 0.3ng/mL and 1.0ng/mL respectively. Intra- and inter-assay accuracy were equal or better than 90% and intra- and inter-assay precision were equal or better than 11.1%. The mean extraction efficiencies were satisfactory being equal or higher than 85.4%. THCA-A was stable in whole blood samples after 3 freeze/thaw cycles and storage at 4°C for 7 days. Re-injection (autosampler) stability was also satisfactory. THC was present in all blood samples with levels ranging from 0.7 to 51ng/mL. THCA-A concentrations ranged from 1.0 to 496ng/mL in blood samples and from 1.4 to 824ng/mL in plasma samples. The plasma:blood partition coefficient had a mean value of 1.7 (±0.21, SD). No correlation was found between the degree of intoxication or impairment stated in the police protocols or reports of medical examinations and the detected THCA-A-concentration in blood.
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland; Laboratory of Forensic Medicine and Toxicology, Medical School, Aristotle University, 54124 Thessaloniki, Greece.
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Raikos
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland.
authors.forename: Helene
authors.initials: H
authors.lastname: Schmid
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland.
authors.forename: Susanne
authors.initials: S
authors.lastname: Nussbaumer
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland.
authors.forename: Lars
authors.initials: L
authors.lastname: Ambach
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland.
authors.forename: Stephan
authors.initials: S
authors.lastname: Lanz
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Längin
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland.
authors.forename: Stefan
authors.initials: S
authors.lastname: König
authors.affiliation: Institute of Forensic Medicine, Forensic Toxicology, University Medical Center Freiburg, Albertstrasse 9, 79104 Freiburg, Germany.
authors.forename: Nadine
authors.initials: N
authors.lastname: Roth
authors.affiliation: Institute of Forensic Medicine, Forensic Toxicology, University Medical Center Freiburg, Albertstrasse 9, 79104 Freiburg, Germany.
authors.forename: Volker
authors.initials: V
authors.lastname: Auwärter
authors.affiliation: Institute of Forensic Medicine, University of Bern, Bühlstr. 20, CH 3012 Bern, Switzerland. Electronic address: Wolfgang.Weinmann@irm.unibe.ch.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Weinmann
mesh_terms: D001334:Automobile Driving / Q000331:legislation & jurisprudence*; D002853:Chromatography, Liquid; D013759:Dronabinol / Q000031:analogs & derivatives* / Q000097:blood; D006801:Humans; D057230:Limit of Detection; D002189:Marijuana Abuse / Q000175:diagnosis; D013058:Mass Spectrometry; D015813:Substance Abuse Detection / Q000379:methods*; D013557:Switzerland
chemical_list: D013759:Dronabinol; C025351:delta(9)-tetrahydrocannabinolic acid
keywords: Delta-9-tetrahydrocannabinolic acid A; Impairment; LC–MS/MS; Plasma; Whole blood