Centre for Forensic Science, University of Technology Sydney (UTS), Broadway, NSW 2007, Australia.
Forensic Sci Int. 2013 Apr 10;227(1-3):69-73. doi: 10.1016/j.forsciint.2012.11.006. Epub 2012 Dec 4.
Oral fluid is currently used by Australian and international law enforcement agencies and employers to detect recent use of cannabis and other drugs of abuse. The main psychoactive constituent of cannabis, Δ(9)-tetrahydrocannabinol (THC), is highly lipophilic and losses occur when in contact with plastic, possibly due to its adsorption onto the plastic surface. This study aims to investigate factors governing the interaction of THC with plastic and search for ways of overcoming such interaction so to improve THC recovery. As polypropylene is one of the most common types of plastic used in collection devices, it was the focus of this study. All experiments were done by preparing neat oral fluid samples spiked with THC in 2-mL polypropylene centrifuge tubes. Samples were transferred with or without prior addition of Triton(®) X-100 (0.25%) to glass tubes containing d3-THC as internal standard and 0.1M phosphate buffer was then added. Samples were extracted by liquid-liquid extraction using hexane/ethyl acetate (9:1, v/v), dried and analysed by gas chromatography-mass spectrometry (GC-MS) after derivatisation. No significant difference was found in terms of THC loss to plastic when the concentration ranged from 25 to 1000 ng/mL in the same volume of oral fluid. Varying the oral fluid volume (0.5-1.5 mL) while keeping THC at a constant concentration showed an upward trend with more loss associated with lower volumes. The use of Triton(®) X-100 significantly decreased the adherence of THC to the plastic tubes and increased the THC transfer (>96%) at all volumes tested. Degradation of THC during storage was also studied over a 4-week period and it was found that azide did not seem to play a significant role in preserving THC in oral fluid.
目前，澳大利亚和国际执法机构以及雇主都在使用口腔液来检测近期大麻和其他药物的使用情况。大麻的主要精神活性成分Δ(9)-四氢大麻酚（THC）具有很强的亲脂性，与塑料接触时会发生损失，这可能是由于其吸附在塑料表面上。本研究旨在调查 THC 与塑料相互作用的因素，并寻找克服这种相互作用的方法，以提高 THC 的回收率。由于聚丙烯是收集装置中最常用的塑料类型之一，因此本研究集中在它身上。所有实验均通过在 2-mL 聚丙烯离心管中制备含有 THC 的纯口腔液样品来完成。将样品转移到含有或不含有 Triton(®) X-100（0.25%）的玻璃管中，添加内部标准 d3-THC 和 0.1M 磷酸盐缓冲液。然后通过使用己烷/乙酸乙酯（9:1，v/v）进行液-液萃取提取样品，干燥后通过衍生化进行气相色谱-质谱（GC-MS）分析。在相同体积的口腔液中，当 THC 浓度在 25 至 1000ng/mL 范围内变化时，发现 THC 向塑料的损失没有明显差异。在保持 THC 浓度不变的情况下，改变口腔液体积（0.5-1.5mL），损失量呈上升趋势，与较低体积相关的损失量更大。使用 Triton(®) X-100 可显著减少 THC 对塑料管的附着，并增加所有测试体积的 THC 转移（>96%）。还研究了在 4 周的储存期间 THC 的降解情况，发现叠氮化物似乎在保护口腔液中的 THC 方面没有发挥重要作用。
