Che Peng, Chang Christina, Buzzini Patrick, Stegemann Lavinia, Kool Jeroen, Davidson J Tyler, Kohler Isabelle
Vrije Universiteit Amsterdam, Amsterdam Institute of Molecular and Life Sciences (AIMMS), Department of Chemistry and Pharmaceutical Sciences, Division of BioAnalytical Chemistry, Amsterdam, the Netherlands; Center for Analytical Sciences Amsterdam (CASA), Amsterdam, the Netherlands.
Sam Houston State University, Department of Forensic Science, Huntsville, TX, USA.
Anal Chim Acta. 2024 Aug 29;1319:342949. doi: 10.1016/j.aca.2024.342949. Epub 2024 Jul 6.
Synthetic cathinones (SCs) are a large category of new psychoactive substances (NPS), which pose a serious threat to public health due to limited information about their toxicology and pharmacology. Many SCs are closely related in their chemical structures, with some substances being positional isomers. In this study, we propose a new workflow for the identification of SC isomers using liquid chromatography-high-resolution tandem mass spectrometry (LC-HRMS) combined with electron activated dissociation (EAD) and chemometrics. Differentiation between isomeric SCs is essential for both legislative and public safety reasons, since minor differences in their molecular structures may change their legal status and pharmacological profiles.
The workflow was optimized using ring-substituted isomers of methylmethcathinones, methylethcathinones, and chloromethcathinones. The kinetic energy in the EAD cell was investigated at three levels (i.e., 15, 18, and 20 eV) for each group. Two data analysis methods (i.e., t-distributed stochastic neighbor embedding [t-SNE] and a Random Forest [RF] algorithm) were applied using the obtained EAD mass spectral data. The three sets of ring-substituted SCs were clearly distinguished using t-SNE and an RF algorithm. Moreover, the RF approach resulted in a 97 % classification accuracy for isomer identification using various combinations of compounds, isomers, and electron kinetic energies. This workflow was subsequentially applied to the analysis of 26 blind street samples, resulting in a 92 % classification accuracy for isomer identification. However, the accuracy varied based on the kinetic electron energy. A subset of the original data set, focusing on 15-eV data only, was used, resulting in a classification accuracy of 100 %.
This study presents the first LC-HRMS workflow based on EAD and chemometrics, which resulted in a classification accuracy of 100 % of authentic street samples. The developed LC-HRMS workflow demonstrates that EAD product ions and their characteristic ion ratios can be successfully used to identify ring-substituted positional isomers of SCs.
合成卡西酮（SCs）是一大类新型精神活性物质（NPS），由于其毒理学和药理学信息有限，对公众健康构成严重威胁。许多SCs在化学结构上密切相关，有些物质是位置异构体。在本研究中，我们提出了一种新的工作流程，用于使用液相色谱 - 高分辨率串联质谱（LC - HRMS）结合电子活化解离（EAD）和化学计量学来鉴定SC异构体。区分异构体SCs对于立法和公共安全都至关重要，因为它们分子结构上的微小差异可能会改变其法律地位和药理学特征。
使用甲基甲基卡西酮、甲基乙基卡西酮和氯甲基卡西酮的环取代异构体对工作流程进行了优化。对每组在三个水平（即15、18和20 eV）下研究了EAD池中动能。使用获得的EAD质谱数据应用了两种数据分析方法（即t分布随机邻域嵌入[t - SNE]和随机森林[RF]算法）。使用t - SNE和RF算法可清晰区分三组环取代SCs。此外，表示方法使用化合物、异构体和电子动能的各种组合，RF方法在异构体鉴定方面的分类准确率达到97%。此工作流程随后应用于26个盲法街头样本的分析，异构体鉴定的分类准确率为92%。然而，准确率因电子动能而异。使用仅关注15 eV数据的原始数据集的一个子集，分类准确率达到100%。
本研究提出了首个基于EAD和化学计量学的LC - HRMS工作流程，对真实街头样本的分类准确率达到100%。所开发的LC - HRMS工作流程表明，EAD产物离子及其特征离子比可成功用于鉴定SCs的环取代位置异构体。
