Mass Spectrometry
Online ISSN : 2186-5116
Print ISSN : 2187-137X
ISSN-L : 2186-5116
Original Article
Generation and Propagation of MALDI Ion Packets Probed by Sheet-Like Nanosecond UV Laser Light
Tatsuro ShirotaKennosuke Hoshina
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2018 Volume 7 Issue 1 Pages A0071


A sheet-like ultraviolet (UV) probe laser is used to investigate the ejection and propagation of ion packets of matrix CHCA, which are produced by matrix-assisted laser desorption and ionization (MALDI). Laser irradiation of the expanding MALDI plume induced photodissociation of the CHCA-related ions, which existed in a sheet-like volume, leading to their absence in their MALDI signal profiles. The MALDI spectra were measured under varying conditions: the temporal delay of the lasers and the distance of the sheet-like probe laser from the MALDI sample surface. It was found that the center of the (CHCA)H+ packets were ejected at 46±11 ns after MALDI laser irradiation, while the (CHCA)2H+ packets were ejected at 64±12 ns, regardless of the magnitude of acceleration static high-voltage in 3.5–5.5 kV. This suggests that (CHCA)2H+ is formed by a proton transfer reaction from (CHCA)H+ to (CHCA)2 in the heated condensed phase and/or near the surface. This study represents the first experimental determination of ion ejection time in the MALDI process, which is also applicable to other species in the MALDI plume.

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© 2018 Tatsuro Shirota and Kennosuke Hoshina. This is an open access article distributed under the terms of Creative Commons Attribution License, which permits use, distribution, and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
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