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Study on ion formation in electrospray droplet impact secondary ion mass spectrometry
Author(s) -
Asakawa Daiki,
Fujimaki Susumu,
Hashimoto Yutaka,
Mori Kunihiko,
Hiraoka Kenzo
Publication year - 2007
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.3004
Subject(s) - chemistry , ion , protonation , mass spectrometry , electrospray , analytical chemistry (journal) , proton , molecule , electrospray ionization , desorption , analyte , deprotonation , secondary ion mass spectrometry , cluster (spacecraft) , static secondary ion mass spectrometry , chromatography , organic chemistry , adsorption , physics , quantum mechanics , computer science , programming language
A new type of cluster secondary ion mass spectrometry (SIMS), named electrospray droplet impact (EDI), has been developed in our laboratory. In general, rather strong negative ions as well as positive ions can be generated by EDI compared with conventional SIMS. In this work, various aspects of ion formation in EDI are investigated. The Brønsted bases (proton acceptor) and acids (proton donor) mixed in the analyte samples enhanced the signal intensities of deprotonated molecules (negative ions) and protonated molecules (positive ions), respectively, for analytes. This suggests the occurrence of heterogeneous proton transfer reactions (i.e. M + M′ → [M+H] + + [M′H] − ) in the shockwave‐heated selvedge of the colliding interface between the water droplet and the solid sample deposited on the metal substrate. EDI‐SIMS shows a remarkable tolerance to the large excess of salts present in samples. The mechanism for desorption/ionization in EDI is much simpler than those for MALDI and SIMS because only very thin sample layers take part in the shockwave‐heated selvedge and complicated higher‐order reactions are largely suppressed. Copyright © 2007 John Wiley & Sons, Ltd.