Knochenmuss Richard
Novartis Institutes for Biomedical Research, Basel, Switzerland.
Analyst. 2006 Sep;131(9):966-86. doi: 10.1039/b605646f. Epub 2006 Jul 27.
Matrix Assisted Laser Desorption/Ionization (MALDI) is a very widely used analytical method, but has been developed in a highly empirical manner. Deeper understanding of ionization mechanisms could help to design better methods and improve interpretation of mass spectra. This review summarizes current mechanistic thinking, with emphasis on the most common MALDI variant using ultraviolet laser excitation. A two-step framework is gaining acceptance as a useful model for many MALDI experiments. The steps are primary ionization during or shortly after the laser pulse, followed by secondary reactions in the expanding plume of desorbed material. Primary ionization in UV-MALDI remains somewhat controversial, the two main approaches are the cluster and pooling/photoionization models. Secondary events are less contentious, ion-molecule reaction thermodynamics and kinetics are often invoked, but details differ. To the extent that local thermal equilibrium is approached in the plume, the mass spectra may be straightforwardly interpreted in terms of charge transfer thermodynamics.
基质辅助激光解吸/电离（MALDI）是一种应用广泛的分析方法，但其发展过程具有高度的经验性。深入理解电离机制有助于设计更好的方法并改进质谱解释。本综述总结了当前的机理认识，重点关注使用紫外激光激发的最常见MALDI变体。一个两步框架正逐渐被认可为许多MALDI实验的有用模型。第一步是在激光脉冲期间或之后不久发生的初级电离，随后是在解吸物质的膨胀羽流中的二级反应。紫外-MALDI中的初级电离仍存在一定争议，两种主要方法是簇模型和聚集/光电离模型。二级事件的争议较小，常涉及离子-分子反应热力学和动力学，但细节有所不同。在羽流中达到局部热平衡的程度上，质谱可以根据电荷转移热力学直接进行解释。
