A survey of useful salt additives in matrix-assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry of lipids: introducing nitrates for improved analysis
A survey of useful salt additives in matrix-assisted laser desorption/ionization mass spectrometry and tandem mass spectrometry of lipids: introducing nitrates for improved analysis
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DOI：
10.1002/rcm.6258
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发表时间：
2012-07-15
影响因子：
2
通讯作者：
Bunch, Josephine
中科院分区：
文献类型：
--
作者：
Griffiths, Rian L.;Bunch, Josephine
原理
基质辅助激光解吸/电离（MALDI）是一种对复杂混合物和薄组织切片中的脂质进行直接分析的强大技术，这使其成为分析健康和疾病状态下脂质概况的极具吸引力的方法。在正离子MALDI质谱（MS）实验中，脂质很容易被检测为[M + H]+、[M + Na]+和[M + K]+离子。这不仅降低了灵敏度，还可能导致不同脂质的各种加合物的质荷比（m/z）值重叠。添加剂可用于促进特定加合物的形成，提高灵敏度，降低光谱复杂性，并在碰撞诱导解离（CID）实验中增强结构表征。
方法
将Li+、Na+、K+、Cs+和NH4+阳离子视为一系列盐类型（醋酸盐、氯化物和硝酸盐），以5到80毫摩尔的浓度掺入二羟基苯甲酸（DHB）基质溶液中。在优化碰撞能量参数后，该研究进一步评估了这些添加剂对一种脂质标准品的CID实验的影响。实验在一台混合四极杆飞行时间（QqTOF）仪器上进行。
结果
对脂质的MALDI - MS和MS/MS中新型和现有添加剂的系统评估表明，添加剂阳离子和阴离子的选择以及浓度对于调整光谱结果非常重要。
结论
添加剂的推荐选择取决于要进行的实验（MS或MS/MS）的预期结果。硝酸盐被发现是脂质分析中特别有用的添加剂。
版权所有（c）2012约翰威立父子有限公司
RATIONALE Matrix-assisted laser desorption/ionization (MALDI) is a powerful technique for the direct analysis of lipids in complex mixtures and thin tissue sections, making it an extremely attractive method for profiling lipids in health and disease. Lipids are readily detected as [M+H]+, [M+Na]+ and [M+K]+ ions in positive ion MALDI mass spectrometry (MS) experiments. This not only decreases sensitivity, but can also lead to overlapping m/z values of the various adducts of different lipids. Additives can be used to promote formation of a particular adduct, improving sensitivity, reducing spectral complexity and enhancing structural characterization in collision-induced dissociation (CID) experiments. METHODS Li+, Na+, K+, Cs+ and NH4+ cations were considered as a range of salt types (acetates, chlorides and nitrates) incorporated into DHB matrix solutions at concentrations between 5 and 80?mM. The study was extended to evaluate the effect of these additives on CID experiments of a lipid standard, after optimization of collision energy parameters. Experiments were performed on a hybrid quadrupole time-of-flight (QqTOF) instrument. RESULTS The systematic evaluation of new and existing additives in MALDI-MS and MS/MS of lipids demonstrated the importance of additive cation and anion choice and concentration for tailoring spectral results. CONCLUSIONS The recommended choice of additive depends on the desired outcomes of the experiment to be performed (MS or MS/MS). Nitrates are found to be particularly useful additives for lipid analysis. Copyright (c) 2012 John Wiley & Sons, Ltd.