| 方 舟1
，孙长海2
，方 芳1*.咖啡酸负离子质谱中2个低质量碎片离子的解析[J].海南师范大学学报自科版,2025,38(1):84-90 |
| 咖啡酸负离子质谱中2个低质量碎片离子的解析 |
| Interpretation of Two Low Mass Fragment Ions In Negative Ion Mass Spectrometry of Caffeic Acid |
| |
| DOI：10.12051/j.issn.1674-4942.2025.01.011 |
| 中文关键词: 咖啡酸 质谱裂解 量子化学计算 乙烯基环戊二烯负离子 乙炔基环戊二烯负离子 |
| 英文关键词: caffeic acid mass spectrometry fragmentation quantum chemical calculation vinyl cyclopentadiene anion ethynyl cyclopentadiene anion |
| 基金项目:黑龙江省卫生健康委科研项目（2020-326） |
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| 摘要点击次数: 240 |
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| 中文摘要: |
| 通过多级质谱的测定与量子化学计算，解析咖啡酸高分辨负离子模式质谱中2个低质
量碎片离子 m/z 91 与 m/z 89 的生成过程与机理。m/z 91 与 m/z 89 分别为咖啡酸去质子分子（m/z
179）裂解的第三代产物与第四代产物离子，2个低质量碎片离子均来自于第二代产物离子m/z 135。
咖啡酸去质子分子脱除CO2生成m/z 135后，m/z 135碎片离子经环骈合、环扩张与脱CO2后可生成
m/z 91碎片离子；而当m/z 135离子脱H2O时则先生成m/z 117的第三代产物离子，而后m/z 117离子
经环收缩脱除CO最终生成m/z 89碎片离子。结合质谱的元素组成，经过渡态、中间产物与碎片离
子的结构优化与计算，得到的m/z 91与m/z 89离子的最优结构分别为乙烯基环戊二烯负离子与乙
炔基环戊二烯负离子。咖啡酸负离子模式质谱中m/z 91离子强度极弱，其原因来自于m/z 91离子
生成途径中的高能垒。 |
| 英文摘要: |
| The formation processes and mechanisms of two low-mass fragment ions at m/z 91 and m/z 89 in high-resolu⁃
tion negative ion mode mass spectrometry of caffeic acid were analyzed by multistage mass spectrometry and quantum
chemistry calculations. The m/z 91 and m/z 89 were the third and fourth generation product ions of deprotonated molecule
of caffeic acid (m/z 179), respectively, and both of the low-mass fragment ions were formed through the second generation
product ion at m/z 135. After the deprotonated molecule of caffeic acid removes CO2 to form m/z 135, the m/z135 fragment
ion can form m/z 91 fragment ion after ring parallization, ring expansion and CO2 removal. When the m/z 135 ion removes
H2O, it first becomes the third generation product ion at m/z 117, and then the m/z 117 ion removes CO by ring contraction
to form the m/z 89 fragment ion. According to the elemental composition of mass spectrometry, the optimal structures of m/z
91 and m/z 89 ions were obtained by optimizing and calculating the structures of transition state, intermediate product and
fragment ion. The optimal structures of m/z 91 and m/z 89 ions were vinyl cyclopentadiene anion and ethynyl cyclopentadiene
anion, respectively. The intensity of m/z 91 ion in the negative ion mode mass spectrometry of caffeic acid is extremely
weak, which is due to the high energy barrier in the m/z 91 ion formation pathway. |
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