Cho Han Soo, Cho Byungseok, Sim Juhyun, Baeck Seung Kyung, In Sangwhan, Kim Eunmi
National Forensic Service, 10 Ipchoon-ro, Wonju, Gangwon-do, 26460, South Korea.
Forensic Sci Int. 2019 Feb;295:219-225. doi: 10.1016/j.forsciint.2018.12.013. Epub 2018 Dec 21.
Cannabis is the second most commonly abused illicit drug after methamphetamine in South Korea. To prove cannabis consumption, 11-nor-9-carboxy-tetrahydrocannabinol (THC-COOH), the metabolite of tetrahydrocannabinol (THC), was screened for in a hair analysis. In this study, we developed a liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis method, which was used to analyze authentic hair samples in 2017. Possible contaminants on the surface of hair samples were eliminated by washing twice each with 2mL of methanol and distilled water. After adding an internal standard (THC-COOH-d), the hair samples (about 20mg each) were digested with 1M NaOH, extracted twice with mixed organic solvents (n-hexane:ethyl acetate), and analyzed by an LC-MS/MS system. Identification and quantification of THC-COOH and THC-COOH-d were performed using a multiple reaction monitoring (MRM) mode at m/z 245 and 191 and m/z 248, respectively (quantifier ions are underlined). The following validation parameters were evaluated: selectivity, linearity, limit of detection (LOD), limit of quantification (LOQ), precision, accuracy, matrix effect, and recovery. The LOD and LOQ of the method was 0.1pg/mg. Good linearity was achieved for THC-COOH in the range from 0.1 to 20pg/mg. The method showed an acceptable precision and accuracy, both of which were less than 15% at the three concentrations of THC-COOH (0.2, 1, and 10pg/mg). THC-COOH showed ion suppression at these three concentrations. The concentrations of THC-COOH in the authentic hair samples ranged from 0.10 to 27.30pg/mg (total 586 cases), and its concentrations were classified as low, medium, or high ranges, i.e., 0.10-0.39pg/mg, 0.39-1.99pg/mg, or 1.99-27.30pg/mg, respectively, according to statistical evaluation. This method showed the possibility of replacing the existing gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. However, further development of our LC-MS/MS method is necessary in order to meet the recommended 0.05pg/mg cut-off.
在韩国，大麻是仅次于甲基苯丙胺的第二大最常被滥用的非法药物。为了证明大麻的消费情况，在毛发分析中对四氢大麻酚（THC）的代谢物11-去甲-9-羧基-四氢大麻酚（THC-COOH）进行了筛查。在本研究中，我们开发了一种液相色谱-串联质谱（LC-MS/MS）分析方法，并于2017年用于分析真实毛发样本。毛发样本表面可能的污染物通过分别用2mL甲醇和蒸馏水各洗涤两次来去除。加入内标（THC-COOH-d）后，毛发样本（每份约20mg）用1M氢氧化钠消化，用混合有机溶剂（正己烷：乙酸乙酯）萃取两次，并通过LC-MS/MS系统进行分析。使用多反应监测（MRM）模式分别在m/z 245和191以及m/z 248处对THC-COOH和THC-COOH-d进行鉴定和定量（定量离子下划线标注）。评估了以下验证参数：选择性、线性、检测限（LOD）、定量限（LOQ）、精密度、准确度、基质效应和回收率。该方法的LOD和LOQ为0.1pg/mg。THC-COOH在0.1至20pg/mg范围内具有良好的线性。该方法显示出可接受的精密度和准确度，在THC-COOH的三个浓度（0.2、1和10pg/mg）下两者均小于15%。THC-COOH在这三个浓度下表现出离子抑制。真实毛发样本中THC-COOH的浓度范围为0.10至27.30pg/mg（共586例），根据统计评估，其浓度分为低、中、高范围，即分别为0.10 - 0.39pg/mg、0.39 - 1.99pg/mg或1.99 - 27.30pg/mg。该方法显示出替代现有气相色谱-串联质谱（GC-MS/MS）分析的可能性。然而，为了达到推荐的0.05pg/mg的截断值，我们的LC-MS/MS方法有必要进一步改进。
