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| 咖啡酸质子化分子质谱裂解脱乙烯酮途径 |
| Pathway of Loss Ketene in Caffeic Acid Protonated Molecule Mass Spectrum Fragmentation |
| 投稿时间：2025-01-12 修订日期：2025-03-31 |
| DOI： |
| 中文关键词: 咖啡酸 脱乙烯酮 质谱裂解 量子化学计算 伪三级质谱 |
| 英文关键词: caffeic acid mass spectrometry fragmentation quantum chemical calculation pseudo-MS3 |
| 基金项目:黑龙江省自然科学基金 (LH2024H004) |
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| 中文摘要: |
| 基于量子化学计算与伪三级质谱实验,解析咖啡酸正离子模式高分辨质谱脱乙烯酮途径的过程与机理。质子化的咖啡酸分子(m/z 181)脱乙烯酮途径由4个环节组成。首个环节的前体离子为咖啡酸羰基α碳结合质子的质子化分子,裂解产物是乙烯酮分子和结构为3,4-二羟基苯甲醇正离子的m/z 139离子,接下环节是m/z 139离子脱除CO生成m/z 111离子(邻苯二酚正离子),第三个环节为m/z 111离子脱H2O生成m/z 93离子(2,4-环已二烯酮正离子),最后一个环节是m/z 93离子脱除CO生成m/z 65离子(环戊二烯正离子)。第一个环节脱除乙烯酮的机理是,前体离子中羧酸的羟基转移到羰基的β碳上后解离出CH2CO分子。第一个环节的前体离子在咖啡酸质子化分子异构体中不具优势比例,使得咖啡酸正离子模式质谱脱乙烯酮途径全部环节的产物离子都为低强度质谱峰。 |
| 英文摘要: |
| Based on quantum chemical calculations and pseudo-MS3 experiments, the process and mechanism of the pathway of loss ketene in caffeic acid positive ion mode high-resolution mass spectrometry were analyzed. The pathway of loss ketene of caffeic acid protonated molecule (m/z 181) consists of four steps. The precursor ion of the first step is the protonated molecule of caffeic acid with carbonyl α carbon binding proton, and the product is both the ketene molecule and the m/z 139 ion which the structure is 3,4-dihydroxybenzyl alcohol cation. The next step is the loss of CO from the m/z 139 ion to generate m/z 111 ion (catechol cation). The third step is the loss of H2O from the m/z 111 ion to generate m/z 93 ion (2,4-cyclohexadienone cation). The last step is the loss of CO from the m/z 93 ion to generate m/z 65 ion (cyclopentadiene cation). In the first step, the hydroxyl group of the carboxylic acid in the precursor ion is transferred to the β carbon of the carbonyl group, and then the CH2CO molecule is dissociated. The precursor ions of the first step do not have a dominant proportion in the protonated molecular isomers of caffeic acid, so that the product ions of all steps of the pathway of loss ketene in caffeic acid positive ion mode mass spectrometry are low-intensity peaks. |
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