The specific matrix used in matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) can have an effect on the molecules ionized from a tissue sample. The sensitivity for distinct classes of biomolecules can vary when employing different MALDI matrices. Here, we compare the intensities of various lipid subclasses measured by Fourier transform ion cyclotron resonance (FT-ICR) IMS of murine liver tissue when using 9-aminoacridine (9AA), 5-chloro-2-mercaptobenzothiazole (CMBT), 1,5-diaminonaphthalene (DAN), 2,5-Dihydroxyacetophenone (DHA), and 2,5-dihydroxybenzoic acid (DHB). Principal component analysis and receiver operating characteristic curve analysis revealed significant matrix effects on the relative signal intensities observed for different lipid subclasses and adducts. Comparison of spectral profiles and quantitative assessment of the number and intensity of species from each lipid subclass showed that each matrix produces unique lipid signals. In positive ion mode, matrix application methods played a role in the MALDI analysis for different cationic species. Comparisons of different methods for the application of DHA showed a significant increase in the intensity of sodiated and potassiated analytes when using an aerosol sprayer. In negative ion mode, lipid profiles generated using DAN were significantly different than all other matrices tested. This difference was found to be driven by modification of phosphatidylcholines during ionization that enables them to be detected in negative ion mode. These modified phosphatidylcholines are isomeric with common phosphatidylethanolamines confounding MALDI IMS analysis when using DAN. These results show an experimental basis of MALDI analyses when analyzing lipids from tissue and allow for more informed selection of MALDI matrices when performing lipid IMS experiments.

中文翻译：

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在MALDI成像质谱实验中发现基质对脂质分析的影响。

基质辅助激光解吸/电离成像质谱（MALDI IMS）中使用的特定基质可能会对从组织样本中电离的分子产生影响。当使用不同的MALDI基质时，不同类别的生物分子的灵敏度可能会有所不同。在这里，我们比较了当使用9-氨基idine啶（9AA），5-氯-2-巯基苯并噻唑（CMBT），1,5时，通过鼠肝组织的傅里叶变换离子回旋共振（FT-ICR）IMS测量的各种脂质亚类的强度-二氨基萘（DAN），2,5-二羟基苯乙酮（DHA）和2,5-二羟基苯甲酸（DHB）。主成分分析和接收器工作特性曲线分析显示，基质对不同脂质亚类和加合物的相对信号强度有显着影响。光谱分布图的比较和对每种脂质亚类物种数量和强度的定量评估表明，每种基质均会产生独特的脂质信号。在阳离子模式下，基质应用方法在不同阳离子种类的MALDI分析中发挥了作用。使用DHA的不同方法的比较表明，使用喷雾器时，固体和钾化分析物的强度显着增加。在负离子模式下，使用DAN生成的脂质谱与所有其他测试基质显着不同。发现这种差异是由电离过程中磷脂酰胆碱的修饰驱动的，该修饰使它们能够以负离子模式被检测到。这些修饰的磷脂酰胆碱与常见的磷脂酰乙醇胺同分异构，在使用DAN时会混淆MALDI IMS分析。这些结果显示了在分析组织中的脂质时进行MALDI分析的实验基础，并在进行脂质IMS实验时可以更明智地选择MALDI基质。