Department of Laboratory Medicine, University of California San Francisco, and Zuckerberg San Francisco General Hospital, San Francisco, CA, USA.
J Anal Toxicol. 2019 Jun 1;43(5):331-339. doi: 10.1093/jat/bkz023.
As the legalization of medical and recreational marijuana use expands, measurement of tetrahydrocannabinol (THC) in human breath has become an area of interest. The presence and concentration of cannabinoids in breath have been shown to correlate with recent marijuana use and may be correlated with impairment. Given the low concentration of THC in human breath, sensitive analytical methods are required to further evaluate its utility and window of detection. This paper describes a novel derivatization method based on an azo coupling reaction that significantly increases the ionization efficiency of cannabinoids for LC-MS/MS analysis. This derivatization reaction allows for a direct derivatization reaction with neat samples and does not require further sample clean-up after derivatization, thus facilitating an easy and rapid "derivatize & shoot" sample preparation. The derivatization assay allowed for limits of quantitation (LOQ's) in the sub-pg/mL to pg/mL range for the five cannabinoids in breath samples, i.e., only 5~50 femtograms of an analyte was required for quantitation in a single analysis. This ultrahigh sensitivity allowed for the quantitation of cannabinoids in all breath samples collected within 3 hours of smoking cannabis (n = 180). A linear correlation between THC and cannabinol (CBN) in human breath was observed, supporting the hypothesis that CBN is converted from THC during the combustion of cannabis. The derivatization method was also applied to the analysis of cannabinoids in whole blood samples, achieving LOQ's at ten-pg/mL to sub-ng/mL level. This azo coupling-based derivatization approach provided the needed analytical sensitivity for the analysis of THC in human breath samples using LC-MS/MS and could be a valuable tool for the analysis of other aromatic compounds in the future.
随着医用和娱乐用大麻合法化的不断扩大，四氢大麻酚（THC）在人呼出气中的测量已成为研究热点。已证明呼气中大麻素的存在和浓度与近期大麻使用情况相关，且可能与损害相关。鉴于人呼出气中 THC 的浓度较低，因此需要使用灵敏的分析方法来进一步评估其效用和检测窗口。本文描述了一种基于偶联反应的新型衍生化方法，该方法显著提高了 LC-MS/MS 分析中大麻素的离子化效率。这种衍生化反应允许在纯样品中直接进行衍生化反应，并且在衍生化后不需要进一步的样品净化，从而便于轻松快速的“衍生化和进样”样品制备。衍生化分析允许在呼出气样本中对五种大麻素进行亚 pg/mL 至 pg/mL 范围内的定量限（LOQ）检测，即在单次分析中仅需 5~50 飞克分析物即可进行定量。这种超高灵敏度允许对吸食大麻后 3 小时内收集的所有呼出气样本中的大麻素进行定量（n = 180）。在人呼出气中观察到 THC 和大麻醇（CBN）之间的线性相关性，这支持了 CBN 在大麻燃烧过程中由 THC 转化而来的假设。该衍生化方法还应用于全血样本中大麻素的分析，在 10 pg/mL 至亚 ng/mL 水平实现了定量限。这种基于偶氮耦合的衍生化方法为使用 LC-MS/MS 分析人呼出气中的 THC 提供了所需的分析灵敏度，并且可能成为未来分析其他芳香族化合物的有用工具。
