Knochenmuss R, Stortelder A, Breuker K, Zenobi R
Laboratory for Organic Chemistry, Swiss Federal Institute of Technology, Universitatsstrasse 16, 8092 Zurich, Switzerland.
J Mass Spectrom. 2000 Nov;35(11):1237-45. doi: 10.1002/1096-9888(200011)35:11<1237::AID-JMS74>3.0.CO;2-O.
Ion-molecule charge- and proton-transfer reactions in the desorption plume are considered for the case of matrix-assisted laser desorption/ionization (MALDI) with ultraviolet laser excitation, and it is proposed that they are major determinants of the observed mass spectrum. Specific MALDI phenomena which are discussed include the dominance of singly charged ions and analyte-matrix or analyte-analyte signal suppression. Should any be formed, highly charged products can be reduced by reaction with neutral matrix, yet singly charged ions cannot generally be neutralized in the same manner. Ion suppression effects can also be explained by similar reactions, which in some cases involve interconversion of dissimilar ion types. The plume is proposed often to be more under thermodynamic rather than kinetic control owing to these secondary reactions. UV/MALDI mass spectra should therefore be largely predictable, given sufficient thermodynamic information, and appropriate experimental conditions of sufficient analyte and plume density. Copyright 2000 John Wiley & Sons, Ltd.
对于采用紫外激光激发的基质辅助激光解吸/电离（MALDI）情况，考虑了解吸羽流中的离子 - 分子电荷转移和质子转移反应，并提出这些反应是所观察到的质谱的主要决定因素。所讨论的特定MALDI现象包括单电荷离子的优势以及分析物 - 基质或分析物 - 分析物信号抑制。如果形成了高电荷产物，可以通过与中性基质反应将其还原，但单电荷离子通常不能以相同方式被中和。离子抑制效应也可以用类似反应来解释，在某些情况下，这些反应涉及不同离子类型的相互转化。由于这些二级反应，通常认为羽流更多地受热力学而非动力学控制。因此，鉴于足够的热力学信息以及足够的分析物和羽流密度的适当实验条件，UV/MALDI质谱在很大程度上应该是可预测的。版权所有2000约翰威立父子有限公司。
