咖啡酸负离子模式质谱奇电子离子碎片的解析  

Analysis of odd electron ion fragments in caffeic acid negative ion mode mass spectrometry

作　　者：方芳[1] 方舟[1] 孙长海[2] FANG Fang;FANG Zhou;SUN Changhai(School of Clinical Medicine,Jiamusi University,Jiamusi 154003,China;College of Pharmacy,Jiamusi University,Jiamusi 154007,China)

机构地区：[1]佳木斯大学临床医学院,黑龙江佳木斯154003 [2]佳木斯大学药学院,黑龙江佳木斯154007

出　　处：《化学分析计量》2024年第10期34-38,共5页Chemical Analysis And Meterage

基　　金：黑龙江省卫生健康委科研项目(2020-326)。

摘　　要：通过高分辨质谱的测定与密度泛函理论方法的计算,揭示咖啡酸电喷雾负离子模式质谱的奇电子离子产生过程与机理。咖啡酸去质子分子裂解产生3个奇电子离子,分别为咖啡酸质谱裂解的第三代产物离子m/z 134(C_(8)H_(6)O_(2))、第四代产物离子m/z 108(C_(6)H_(4)O_(2))和m/z 106(C_(7)H_(6)O)。m/z 134离子来自于其前体离子m/z 135(3,4-二羟基苯乙烯离子)羟基O—H键的直接均裂,因其裂解过程较m/z 135的其他裂解相对简单并且所需能量相对较少,使质谱中m/z 134峰强度较大。m/z 108与m/z 106离子的前体离子可以是偶电子离子m/z 109(邻苯二酚离子)和m/z 107(2-羟基环戊二烯离子),也可以是奇电子离子m/z 134。m/z 108与m/z 106离子来自于偶电子离子时,m/z 109的O—H键直接发生均裂,m/z 107离子的O—H键经过渡态发生均裂。The generation process and mechanism of odd electron ions in caffeic acid electrospray negative ion mode mass spectrometry were revealed by the determination of high resolution mass spectrometry and the calculation of density functional theory.The fragmentation of caffeic acid deprotonated molecule produces three odd electron ions,which are the third generation product ion m/z 134(C_(8)H_(6)O_(2))and the fourth generation product ion m/z 108(C_(6)H_(4)O_(2))and m/z 106(C_(7)H_(6)O)of caffeic acid mass spectrometry cleavage.The m/z 134 ion originates from the direct homolytic dissociation of the O—H bond of the phenolic hydroxyl group of its precursor ion m/z 135(3,4-dihydroxystyrene ion),Due to its relatively simple dissociation process and relatively less energy required compared to other m/z 135 fragmentation processes,the intensity of the m/z 134 ion peak in mass spectrometry is higher.The precursor ions of m/z 108 and m/z 106 ion can be even electron ions m/z 109(catechol ion)and m/z 107(2-hydroxycyclopentadiene ion)or odd electron ions m/z 134.When m/z 108 and m/z 106 ions come from even electron ions,the O—H bond of m/z 109 is directly homolytic dissociation,while the O—H bond of m/z 107 is homolytic dissociation through a transition state.

关 键 词：咖啡酸 质谱裂解 量子化学计算 奇电子离子 

分 类 号：O657.6[理学—分析化学]