Wavelength dependence of UV-MALDI mass spectrometry and of direct UV-LDI-MS without matrix

在MALDI质谱仪中，分析灵敏度受激发激光波长的影响很大。在研究项目的第一个资助期，首次利用一组选定的基质体系和多肽作为分析物，在280-377 nm的波长范围内系统地研究了UV-MALDI的解吸和电离机理。这些结果表明，通过调整激光波长以适应基质的单个吸收峰，可以显著提高分析性能。第二个资助期将在几个重要方面以这些成果为基础。将全面描述已建立的MALDI矩阵及其使用的分析物类别的改进潜力。优化的矩阵波长系统将提供更高的分析灵敏度，将应用于空间分辨组织成像MS(MALDI-MSI)。在标准基质旁边，将描述允许产生高带电多肽离子的液体基质系统。将波长范围扩展到213-450 nm还允许探索新的分析可能性，其中包括，例如，无基质UV-LDI-MS分析小分子和组织中代谢物的UV-LDI-MSI分析。这些研究还将加深我们对MALDI基本机制的了解。

In MALDI mass spectrometry, analytical sensitivity is largely influenced by the wavelength of the excitation laser. In the 1st funding period of the research project, the UV-MALDI desorption and ionization mechanisms were for the first time investigated systematically in the wavelength range of 280-377 nm by utilizing a selected set of matrix systems and peptides as analytes. These results showed that analytical performance can be substantially enhanced by adjusting the laser wavelength to the individual peak absorption of matrices. The 2nd funding period will build on these results in several important aspects. Established MALDI matrices and the analyte classes for which they are utilized will be comprehensively characterized with respect to the potential for improvement. Optimized matrix-wavelength systems that offer improved analytical sensitivity will be applied to spatially-resolved tissue imaging MS (MALDI-MSI). Next to standard matrices, liquid matrix systems that allow the generation of highly charged peptide ions will be characterized. Extension of the wavelength range to 213-450 nm furthermore allows to explore novel analytical possibilities, among which are, for example, the analysis of small molecules by matrix-free UV-LDI-MS and the UV-LDI-MSI analysis of metabolites in tissue. The studies will also deepen our knowledge about the basic MALDI mechanisms.