Affiliation:
1. Center for Forensic Hair Analytics, Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
2. Department of Forensic Pharmacology and Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, Zurich, Switzerland
Abstract
Abstract
In forensic toxicology, high-performance liquid chromatography tandem mass spectrometry (LC-MS/MS) is increasingly used for the fast and sensitive measurement of a wide range of drugs. For our routine casework, a liquid chromatography atmospheric pressure chemical ionization-tandem mass spectrometry (LC-APCI-MS/MS) method for the quantification of Δ9-tetrahydrocannabinol (Δ9-THC), cannabinol (CBN) and cannabidiol (CBD) in hair was established and fully validated. Separation was achieved using a Kinetex® C18 column (100 mm × 2.1 mm, 100 Å, 1.7 μm, Phenomenex) at a flow rate of 0.5 mL/min. Measurements were performed on a QTrap 5,500 mass spectrometer (Sciex, Darmstadt, Germany). Unexpected signals were observed in authentic THC-positive hair samples. First, a signal with a slightly shifted retention time of THC whose origin could be assigned to the isomer Δ8-THC. Second, additional peaks exhibiting the same fragments as CBN and Δ9-THC but eluting at different retention times were detected. Spiking experiments and enhanced product ion scans (EPI) pointed to the origin of these additional signals as result of in-source decarboxylation of Δ9-tetrahydrocannabinolic acid A (Δ9-THCA-A) into Δ9-THC and further partial oxidation of Δ9-THC into CBN, respectively. Positive findings of Δ9-THCA-A in hair have been shown to derive from external contamination, therefore, the herein described artefacts may be used as indirect markers for external contamination.
Publisher
Oxford University Press (OUP)
Subject
Chemical Health and Safety,Health, Toxicology and Mutagenesis,Toxicology,Environmental Chemistry,Analytical Chemistry
Cited by
8 articles.
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