【目的】利用超高效液相色谱与串联四级杆飞行时间质谱仪联用技术（ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry，UPLC-Q-TOF-MS/MS）结合质谱裂解规律分析，靶向分离Alternaria panax发酵液粗提物中次生代谢产物。【方法】用马铃薯葡萄糖（potato dextrose broth，PDB）培养基液体发酵A.panax 14 d，将滤液用乙酸乙酯萃取后减压浓缩得粗提物；基于UPLC-Q-TOF-MS/MS方法（高分辨质谱、分子式与碎片峰等）分析粗提物化学成分及质谱裂解规律；采用半制备高效液相色谱（high-performance liquid chromatography，HPLC）方法进一步分离纯化；结合核磁共振波谱（nuclear magnetic resonance，NMR）和质谱（mass spectrometry，MS）等谱学技术以及与文献数据对照确定化合物结构。【结果】利用UPLC-Q-TOF-MS/MS技术分析出A.panax发酵液中存在9个二酮哌嗪类化合物（1-9），并分析其质谱裂解规律；为验证结构推测的准确性，靶向分离鉴定了化合物1-3，结合高分辨质谱数据，靶向分离得到的化合物结构与质谱分析结构一致。【结论】UPLC-Q-TOF-MS/MS技术结合质谱裂解规律能够快速、高效地完成样品中目标成分的分析，并可以指导化合物的靶向分离。
[Objective] To obtain the target compounds from the extract of Alternaria panax based on ultra-high-performance liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (UPLC-Q-TOF-MS/MS) combined with their fragmentation patterns. [Methods] A. panaxwas fermented in potato dextrose broth(PDB) for 14 days. The filtrate was extracted with ethyl acetate and concentrated under reduced pressure to obtain the crude extract. The chemical composition and fragmentation pattern of the crude extract of A. panax were analyzed by UPLC-Q-TOF-MS/MS (including high-resolution electrospray ionization mass spectrometry (HR-ESI-MS), molecular formula, and fragment peak). Semi-preparative high-performance liquid chromatography (HPLC) was employed to further purify the target compounds. The structures of the compounds were identified by nuclear magnetic resonance (NMR), mass spectrometry (MS), and comparison with literature data. [Results] Nine diketopiperazines (1-9) were identified by UPLC-Q-TOF-MS/MS from the crude extract of A. panax and their fragmentation patterns were analyzed. To verify the correctness of these structures, we separated compounds 1-3 and determined their chemical structures. The obtained structures of compounds 1-3 were consistent with the results of UPLC-Q-TOF-MS/MS. [Conclusion] UPLC-Q-TOF-MS/MS combined with fragmentation patterns can rapidly and efficiently identify the target components in an unknown sample, which can guide the targeted isolation as well.