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Double cation adduction in matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry of electron deficient anthraquinone derivatives
Author(s) -
Lou Xianwen,
Sinkeldam Renatus W.,
van Houts Wouter,
Nicolas Yohann,
Janssen Pim G. A.,
van Dongen Joost L. J.,
Vekemans Jef A. J. M.,
Meijer E. W.
Publication year - 2007
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/jms.1161
Subject(s) - chemistry , mass spectrometry , double bond , ion , time of flight mass spectrometry , matrix assisted laser desorption/ionization , desorption , anthraquinone , ionization , electron ionization , double ionization , analytical chemistry (journal) , chromatography , organic chemistry , adsorption
Abstract Six anthraquinone derivatives were analyzed using matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI TOF MS). Clear (pseudo) molecular ions were observed for all the compounds. Interestingly, for some derivatives, strong ions with double cation adduction were also recorded in the positive mode. It is remarkable that all these ions are singly charged. In this work, possible mechanisms for the double cation adduction were investigated and discussed. It appears that the double cation adduction was due to the electron deficient nature of the derivatives, and formed by taking up two singly charged cations and one electron. Substituents on the anthraquinone ring were found to have a significant effect on the double cation adduction. In contrast, no considerable influence of the acidity of MALDI matrix/solution was observed, even on the double proton adduction. Furthermore, it was demonstrated that double cation adduction might occur in the MALDI gas‐phase plume. In addition to the anthraquinones, three more electron deficient compounds of different types, i.e. a perylene bisimide derivative (PB), 3,7‐decanoylamino‐4,8‐dihydrobenzo[1,2‐b:4,5‐b′]dithiophene‐4,8‐dione (TQ) and 6,6‐phenyl C 61 ‐butyric acid methyl ester (PCBM), were also analyzed with MALDI TOF MS. The results indicate that the ‘abnormal’ double cation adduction might be a ‘normal’ phenomenon in the MALDI TOF MS analysis of many electron deficient compounds. Copyright © 2007 John Wiley & Sons, Ltd.