原位电离便携式质谱研究卡西酮类毒品的裂解规律和分析策略

采用纸毛细管喷雾（PCS）原位电离便携式质谱，在正离子模式下采集国内列管的40种卡西酮类毒品的质谱信息，分析一级质谱图［M+H］⁺峰，MS²、MS²_DDA模式下的特征碎片峰及其相对丰度比，建立用于40种卡西酮类毒品快速筛查的质谱数据库。研究发现，所有卡西酮类毒品均存在α位的C—N键裂解；根据最高离子峰是否为［M-H₂O+H］⁺碎片峰可推测其是否存在仲、叔胺结构；N上取代基为吡咯烷基的卡西酮类毒品存在m/z 98+C_nH_2n系列特征峰；苯环上取代基为亚甲二氧基的卡西酮类毒品存在［M+H］⁺峰失去48 u或非［M+H］⁺峰失去30 u的特征离子峰。设计推断未知卡西酮类化合物的分析策略，并成功应用于10种待测物的结构推断。本方法可为卡西酮类毒品的结构鉴定和现场办案提供数据支持，有望成为打击卡西酮类毒品犯罪新的研判思路。

Study the Fragmentation Characteristics and Analysis Strategy of Cathinones by Ambient Ionization Portable Mass Spectrometry

Paper-capillary spray modified on the basis of paper spray ionization in order to facilitate the combination with portable mass spectrometry is an ambient ionization technique, which can be uesd to detect compounds rapidly without the restriction of location and environment. Paper-capillary spray and ambient ionization portable mass spectrometry in positive ion mode were used to collect mass spectrum information of 40 kinds of cathinones controlled in China. The ［M+H］⁺ peak of MS¹, the characteristic fragment ions of MS² and MS²_DDA mode and their relative abundance ratio were analyzed. The obtained mass spectrum information was used to establish a database for the rapid screening of 40 cathinones. It was found that C—N cleavage at the α site existed in all the cathinones through the study of their fragmentation characteristics. Whether the highest ion peak was ［M—H₂O+H］⁺ fragment peak could infer the existence of secondary and tertiary amine structures. A series of characteristic peaks of m/z 98+C_nH_2n would exist when the N was substituted by pyrrolidinyl. The characteristic ion of ［M+H］⁺ lost 48 u or that of non ［M+H］⁺ lost 30 u would exist when the benzene ring was substituted by methylenedioxy. The fragmentation characteristics were studied to design and establish a complete analysis strategy for the unknown cathinones. The strategy could be applied in the following three aspects. 1) To judge whether they are cathinones; 2) To judge whether they are 40 kinds of cathinones in the database; 3) To infer the characteristic structure of cathinones outside the scope of the database. The strategy was successfully used for the structural identification of 10 analytes, which included the common categories of drugs controlled in China. No interference or misjudgment was found, and the database could be used normally. The structures inferred by the analysis strategy were consistent with the actual structure, and the isomers involved would also be distinguished because of their different fragment ions, indicating that this scheme was feasible. This method only needs simple sample loading operation and integrated small mass spectrometer, and is not limited by location and environment. In the investigation of such drug cases, this method can carry out rapid screening and timely feedback, which plays an important role in the rapid and accurate crackdown on the crime of cathinones and it is expected to be a new way to study and judge the crime of cathinones.