2,5-Dihydroxybenzoic acid salts for matrix-assisted laser desorption/ionization time-of-flight mass spectrometric lipid analysis: Simplified spectra interpretation and insights into gasphase fragmentation
2,5-Dihydroxybenzoic acid salts for matrix-assisted laser desorption/ionization time-of-flight mass spectrometric lipid analysis: Simplified spectra interpretation and insights into gasphase fragmentation
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DOI：
10.1002/rcm.6910
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发表时间：
2014-06-30
影响因子：
2
通讯作者：
Schiller, Juergen
中科院分区：
文献类型：
--
作者：
Jaskolla, Thorsten W.;Onischke, Kristin;Schiller, Juergen
在过去的几十年里，人们对脂质作为膜的重要组成部分的兴趣大大增加。如今，脂质通常通过基质辅助激光解吸/电离飞行时间质谱（MALDI-TOF MS）进行常规分析。在这方面，许多相关方面迄今尚不清楚，例如，气相稳定性、加合物形成和碎裂。为了填补这一空白，提出了MALDI基质盐，其允许简化脂质分析和阐明潜在的气相裂解机制。高灵敏度、简单的样品制备和对污染物的高耐受性。将常用的MALDI基质2，5-二羟基苯甲酸的合成的近中性Na+和NH 4+盐的脂质水解、电离和碎裂性质与DHB游离酸本身的性质以及与在干滴样品制备期间向DHB中添加的碱的性质进行比较。当用经典的酸性基质通过MALDI分析时，磷脂酰胆碱和β-乙醇胺经历初始质子化，随后迅速部分直至定量断裂。中性基质盐可以通过抑制分析物质子化来防止初始分析物碎裂。此外，由于阳离子螯合作用使分析物稳定，分子内气相裂解反应可被抑制。在样品制备过程中的碱添加导致不仅在原位生成的基质盐，但也分析物hydrolyzation. CONCLUSIONSNutral DHB盐避免分离的脂质物种成几个电离状态时，用作基质的MALDI-TOF MS。这允许简化脂质光谱的解释。由于DHB基质盐的高阳离子化效率，使用标准酸性DHB不能容易地分析的某些脂质类别变得可检测。版权所有（c）2014约翰威利父子有限公司
RATIONALEIn the last decades the interest in lipids as important components of membranes has considerably increased. Nowadays, lipids are often routinely analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). In this regard, many relevant aspects are so far unknown, e.g., gas-phase stabilities, adduct formation and fragmentation. To fill this gap, MALDI matrix salts are presented which allow for simplified lipid analysis and elucidation of the underlying gas-phase fragmentation mechanisms.METHODSMALDI-TOF MS was used due to its beneficial properties for lipid investigations, e.g., high sensitivity, simple sample preparations, and a high tolerance to contaminants. The lipid hydrolysis, ionization and fragmentation properties of synthesized near neutral Na+ and NH4+ salts of the commonly used MALDI matrix 2,5-dihydroxybenzoic acid were compared to that of DHB free acid itself as well as to base addition to DHB during dried-droplet sample preparation.RESULTSMany lipid classes such as sterols, triacylglycerols, phosphatidylcholines and -ethanolamines undergo initial protonation with subsequent prompt partial up to quantitative fragmentation when analyzed with classical acidic matrices by MALDI-TOF MS. Neutral matrix salts can prevent initial analyte fragmentation by suppression of analyte protonation. Additionally, intramolecular gas-phase fragmentation reactions can be inhibited due to analyte stabilization by cation chelation. Base addition during sample preparation leads not only to in situ generation of matrix salts but also to analyte hydrolysis.CONCLUSIONSNeutral DHB salts avoid separation of lipid species into several ionization states when used as matrices in MALDI-TOF MS. This allows for simplified lipid spectra interpretation. Due to the high cationization efficiency of DHB matrix salts, certain lipid classes become detectable which cannot be analyzed easily using standard acidic DHB. Copyright (c) 2014 John Wiley & Sons, Ltd.