Sodiated lysoglycerophosphatidylethanolamine (LGPE) and lysoglycerophosphatidylcholine (LGPC) species dissociate under low collision energy by covalent bond cleavage resulting in product ions with either sodium retention or without sodium retention. For explaining these fragmentations, sodium chelation by heteroatoms (as charge-solvated structures) is often considered, and consequently, under keV collision conditions, sodium is “spectator” of cleavages (charge remote fragmentation). However, cleavage of such charge-solvated forms under low-energy conditions should result in sodium desolvation rather than covalent bond cleavage. In the present study, protonated salts are proposed as the main representative structures of the sodiated LGPE and LGPC forms. These structures are generated from sodiation of zwitterionic and betaine forms of LGPE and LGPC molecules, respectively. Experimental evidence to determine which structure is involved in the dissociations is provided, especially by comparing the dissociation of LGPL sodiated forms with that of sodiated polyethylene glycols. Energy-resolved mass spectrometry breakdown experiments were performed on a quadrupole time-of-flight instrument to demonstrate that both LGPE and LGPC sodiated forms exist as protonated salt structures. From such structures, proton migration by prototropy can result in different bond cleavages whereas the salt moiety remains spectator of these processes.

中文翻译：

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电喷雾产生的钠化溶血磷脂酯结构的实验证据基本上以质子化盐的形式存在

钠化的溶血甘油磷脂酰乙醇胺 (LGPE) 和溶血甘油磷脂酰胆碱 (LGPC) 物质在低碰撞能量下通过共价键裂解解离，从而产生保留钠或不保留钠的产物离子。为了解释这些碎裂，通常考虑杂原子对钠的螯合（作为电荷溶剂化结构），因此，在 keV 碰撞条件下，钠是裂解（电荷远程碎裂）的“旁观者”。然而，在低能量条件下这种电荷溶剂化形式的裂解应该导致钠去溶剂化而不是共价键裂解。在本研究中，质子化盐被提议作为钠化 LGPE 和 LGPC 形式的主要代表性结构。这些结构分别由两性离子和甜菜碱形式的 LGPE 和 LGPC 分子的钠化作用产生。提供了确定哪种结构参与解离的实验证据，特别是通过比较 LGPL 钠化形式与钠化聚乙二醇的解离。在四极杆飞行时间仪器上进行了能量分辨质谱击穿实验，以证明 LGPE 和 LGPC 钠化形式均以质子化盐结构存在。从这样的结构中，质子通过原性迁移会导致不同的键断裂，而盐部分仍然是这些过程的旁观者。特别是通过比较 LGPL 钠化形式与钠化聚乙二醇的解离。在四极杆飞行时间仪器上进行了能量分辨质谱击穿实验，以证明 LGPE 和 LGPC 钠化形式均以质子化盐结构存在。从这样的结构中，质子通过原性迁移会导致不同的键断裂，而盐部分仍然是这些过程的旁观者。特别是通过比较 LGPL 钠化形式与钠化聚乙二醇的解离。在四极杆飞行时间仪器上进行了能量分辨质谱击穿实验，以证明 LGPE 和 LGPC 钠化形式均以质子化盐结构存在。从这样的结构中，质子通过原性迁移会导致不同的键断裂，而盐部分仍然是这些过程的旁观者。