標題: Fluorescence spectroscopy of UV-MALDI matrices and implications of ionization mechanisms
作者: Lin, Hou-Yu
Hsu, Hsu Chen
Lu, I-Chung
Hsu, Kuo-Tung
Liao, Chih-Yu
Lee, Yin-Yu
Tseng, Chien-Ming
Lee, Yuan-Tseh
Ni, Chi-Kung
應用化學系
Department of Applied Chemistry
公開日期: 28-十月-2014
摘要: Matrix-assisted laser desorption ionization (MALDI) has been widely used in the mass analysis of biomolecules; however, there are a lot of debates about the ionization mechanisms. Previous studies have indicated that S-1-S-1 annihilation might be a key process in the generation of primary ions. This study investigates S-1-S-1 annihilation by examining the time-resolved fluorescence spectra of 12 matrices. No S-1-S-1 annihilation was observed in six of these matrices (3-hydroxy-picolinic acid, 6-aza-2-thiothymine, 2,4-dihydroxy-acetophenone, 2,6-dihydroxy-acetophenone, 2,4,6-trihydroxy-acetophenone, and ferulic acid). We observed two matrix molecules reacting in an electronically excited state (S-1) in five of these matrices (2,5-dihydroxybenzoic acid, alpha-cyano-4-hydroxycinnamic acid, 2,5-dihydroxy-acetophenone, 2,3-dihydroxybenzoic acid, and 2,6-dihydroxybenzoic acid), and S-1-S-1 annihilation was a possible reaction. Among these five matrices, no S-1-S-1 annihilation was observed for 2,3-dihydroxybenzoic acid in typical peak power region of nanosecond laser pulses in MALDI, but a very small value of reaction rate constant was observed only in the high peak power region. The excited-state lifetime of sinapinic acid was too short to determine whether the molecules reacted in an electronically excited state. No correlation was observed between the ion generation efficiency of MALDI and S-1-S-1 annihilation. The results indicate that the proposal of S-1-S-1 annihilation is unnecessary in MALDI and energy pooling model for MALDI ionization mechanism has to be modified. (C) 2014 AIP Publishing LLC.
URI: http://dx.doi.org/10.1063/1.4898372
http://hdl.handle.net/11536/123959
ISSN: 0021-9606
DOI: 10.1063/1.4898372
期刊: JOURNAL OF CHEMICAL PHYSICS
Volume: 141
Issue: 16
顯示於類別:期刊論文


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