Formation and decompositions of chloride adduct ions, [M+Cl]-, in negative ion electrospray ionization mass spectrometry
Formation and decompositions of chloride adduct ions, [M+Cl]-, in negative ion electrospray ionization mass spectrometry
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DOI：
10.1016/s1044-0305(00)00164-1
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发表时间：
2000-11-01
影响因子：
3.2
通讯作者：
Cole, RB
中科院分区：
文献类型：
--
作者：
Zhu, JH;Cole, RB
使用氯仿和四氯化碳等氯化溶剂，开发了在负离子电喷雾电离质谱 (ESI-MS) 中促进 [M + Cl](-) 形式的氯离子附着的能力。该方法能够检测缺乏酸性位点并因此表现出弱 [M - H](-) 信号的分析物，从而扩展了负离子 ESI-MS 的当前功能。与碱金属阳离子加合物在正离子 ESI-MS/MS 中经常观察到的远程碰撞诱导解离 (CID) 不同，氯化物加合物的分解通常通过竞争性解离形成 Cl-（不提供结构信息）或 [M - H](-)。后者可以通过连续分解提供结构信息。对于气相酸度高于HCl的化合物，低CID碰撞能可以促进[M-H](-)的形成，而对于大多数气相酸度低于HCl的化合物，较高的碰撞能通常会提高[M-H](-)的相对产率。由于氯离子附着主要发生在亲电子氢上，因此子离子比 Cl-/[M - H](-) 主要取决于分析物分子和 HCl 之间气相酸度的差异。在较高的碰撞能量下，熵因素在确定产物比率方面变得更加重要。对于一系列取代苯酚和一系列乙酸类似物，已估计了 Cl- 形成和 [M - H](-) 形成的 DeltaS(0) 项之间的差异。最后，报道了甘油磷酸胆碱和神经节苷脂 GM3 甲酯中 CH3Cl 的新中性损失。 (C) 2000 年美国质谱学会。
The ability to promote chloride-attachment ions of the form [M + Cl](-) in negative ion electrospray ionization mass spectrometry (ESI-MS) has been developed using chlorinated solvents such as chloroform and carbon tetrachloride. This approach expands the current capabilities of negative ion ESI-MS by enabling detection of analytes that lack acidic sites and thus exhibit weak [M - H](-) signals. In contrast to the remote-site collision-induced dissociation (CID) often observed in positive ion ESI-MS/MS for alkali metal cation adducts, the decomposition of chloride adducts usually proceeds via competitive dissociations to form Cl-, which is not structurally informative, or [M - H](-). The latter can provide structural information via consecutive decompositions. For compounds having higher gas-phase acidities than HCl, a low CID collision energy can promote the formation of [M - H](-), whereas for the majority of compounds with lower gas phase acidities than HCl, higher collision energies generally improve the relative yield of [M - H](-). Because chloride attachment occurs primarily at electrophilic hydrogens, the daughter ion ratio, Cl-/[M - H](-), depends primarily upon the difference in gas phase acidity between the analyte molecule and HCl. At higher collision energies, entropic factors take on increased importance in determining the product ratio. The difference between the DeltaS(0) terms for formation of Cl- and formation of [M - H](-) has been estimated for a series of substituted phenols and a series of acetic acid analogs. Finally, a novel neutral loss of CH3Cl from glycerophosphocholine and from ganglioside GM3 methyl ester is reported. (C) 2000 American Society for Mass Spectrometry.