Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
Nuclear, Chemistry & Biology Division, Pacific Northwest National Laboratory, Richland, Washington 99354, United States.
J Am Soc Mass Spectrom. 2024 Jul 3;35(7):1609-1621. doi: 10.1021/jasms.4c00200. Epub 2024 Jun 22.
2-Benzylbenzimidazoles, or "nitazenes", are a class of novel synthetic opioids (NSOs) that are increasingly being detected alongside fentanyl analogs and other opioids in drug overdose cases. Nitazenes can be 20× more potent than fentanyl but are not routinely tested for during postmortem or clinical toxicology drug screens; thus, their prevalence in drug overdose cases may be under-reported. Traditional analytical workflows utilizing liquid chromatography-tandem mass spectrometry (LC-MS/MS) often require additional confirmation with authentic reference standards to identify a novel nitazene. However, additional analytical measurements with ion mobility spectrometry (IMS) may provide a path toward reference-free identification, which would greatly accelerate NSO identification rates in toxicology laboratories. Presented here are the first IMS and collision cross section (CCS) measurements on a set of fourteen nitazene analogs using a structures for lossless ion manipulations (SLIM)-orbitrap MS. All nitazenes exhibited two high intensity baseline-separated IMS distributions, which fentanyls and other drug and druglike compounds also exhibit. Incorporating water into the electrospray ionization (ESI) solution caused the intensities of the higher mobility IMS distributions to increase and the intensities of the lower mobility IMS distributions to decrease. Nitazenes lacking a nitro group at the R1 position exhibited the greatest shifts in signal intensities due to water. Furthermore, IMS-MS/MS experiments showed that the higher mobility IMS distributions of all nitazenes possessing a triethylamine group produced fragment ions with / 72, 100, and other low intensity fragments while the lower mobility IMS distributions only produced fragment ions with / 72 and 100. The IMS, solvent, and fragmentation studies provide experimental evidence that nitazenes potentially exhibit three gas-phase protomers. The cyclic IMS capability of SLIM was also employed to partially resolve four sets of structurally similar nitazene isomers (e.g., protonitazene/isotonitazene, butonitazene/isobutonitazene/secbutonitazene), showcasing the potential of using high-resolution IMS separations in MS-based workflows for reference-free identification of emerging nitazenes and other NSOs.
2-苄基苯并咪唑类，或“硝甲西泮”，是一类新型合成阿片类药物（NSO），在药物过量病例中与芬太尼类似物和其他阿片类药物一起被越来越多地检测到。硝甲西泮的效力比芬太尼强 20 倍，但在死后或临床毒理学药物筛查中通常不进行检测；因此，它们在药物过量病例中的流行程度可能被低估。利用液相色谱-串联质谱（LC-MS/MS）的传统分析工作流程通常需要使用真实参考标准进行额外确认，以鉴定新型硝甲西泮。然而，利用离子淌度谱（IMS）进行额外的分析测量可能提供一种无参考识别的途径，这将极大地提高毒理学实验室中 NSO 的鉴定速度。本文首次报道了利用结构无损离子操控（SLIM）-轨道阱质谱对 14 种硝甲西泮类似物进行 IMS 和碰撞截面（CCS）测量。所有硝甲西泮都表现出两个高强度基线分离的 IMS 分布，芬太尼和其他药物和类似物也表现出这种分布。将水纳入电喷雾电离（ESI）溶液中，会导致较高迁移率 IMS 分布的强度增加，而较低迁移率 IMS 分布的强度降低。在 R1 位置缺乏硝基的硝甲西泮表现出由于水而导致的信号强度最大的变化。此外，IMS-MS/MS 实验表明，所有具有三乙胺基团的硝甲西泮的较高迁移率 IMS 分布会产生具有 / 72、100 和其他低强度片段的碎片离子，而较低迁移率 IMS 分布仅产生具有 / 72 和 100 的碎片离子。IMS、溶剂和碎片化研究为硝甲西泮可能表现出三种气相前体提供了实验证据。SLIM 的循环 IMS 能力还被用于部分解析四组结构相似的硝甲西泮异构体（例如，质子硝甲西泮/异硝甲西泮、丁硝甲西泮/异丁硝甲西泮/仲丁硝甲西泮），展示了在基于 MS 的工作流程中使用高分辨率 IMS 分离对新兴硝甲西泮和其他 NSO 进行无参考识别的潜力。
