Center for Forensic Hair Analytics, Zurich Institute of Forensic Medicine, University of Zurich, CH-8006 Zürich, Switzerland.
Department of Forensic Pharmacology and Toxicology, Zurich Institute of Forensic Medicine, University of Zurich, CH-8006 Zürich, Switzerland.
J Anal Toxicol. 2022 May 20;46(5):504-511. doi: 10.1093/jat/bkab056.
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 LC atmospheric pressure chemical ionization 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 5500 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 was detected. 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 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 artifacts may be used as indirect markers for external contamination.
在法医毒理学中，高效液相色谱串联质谱（LC-MS-MS）越来越多地用于快速灵敏地测量广泛的药物。对于我们的常规案例工作，建立并充分验证了一种用于毛发中 Δ9-四氢大麻酚（Δ9-THC）、大麻酚（CBN）和大麻二酚（CBD）定量的 LC 大气压化学电离 MS-MS 方法。分离采用 Kinetex® C18 柱（100 mm×2.1 mm，100 Å，1.7 μm，Phenomenex）在流速为 0.5 mL/min 下实现。测量在 QTRAP 5500 质谱仪（Sciex，达姆施塔特，德国）上进行。在真实的 THC 阳性毛发样本中观察到了意想不到的信号。首先，检测到一种保留时间略有偏移的 THC 信号，其来源可归因于异构体 Δ8-THC。其次，检测到具有与 CBN 和 Δ9-THC 相同的碎片但在不同保留时间洗脱的额外峰。加标实验和增强的产物离子扫描表明，这些额外信号的起源是 Δ9-四氢大麻酸 A（Δ9-THCA-A）在源内脱羧生成 Δ9-THC 以及 Δ9-THC 进一步部分氧化成 CBN 的结果。已经表明毛发中 Δ9-THCA-A 的阳性发现源自外部污染；因此，此处描述的伪影可作为外部污染的间接标志物。
