Lu IC, Chu KY, Lin CY, Wu SY, Dyakov YA, Chen JL, Gray-Weale A, Lee YT, Ni CK. Ion-to-Neutral Ratios and Thermal Proton Transfer in Matrix-Assisted Laser Desorption/Ionization.
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2015;
26:1242-1251. [PMID:
25851654 DOI:
10.1007/s13361-015-1112-3]
[Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Revised: 02/15/2015] [Accepted: 02/16/2015] [Indexed: 06/04/2023]
Abstract
The ion-to-neutral ratios of four commonly used solid matrices, α-cyano-4-hydroxycinnamic acid (CHCA), 2,5-dihydroxybenzoic acid (2,5-DHB), sinapinic acid (SA), and ferulic acid (FA) in matrix-assisted laser desorption/ionization (MALDI) at 355 nm are reported. Ions are measured using a time-of-flight mass spectrometer combined with a time-sliced ion imaging detector. Neutrals are measured using a rotatable quadrupole mass spectrometer. The ion-to-neutral ratios of CHCA are three orders of magnitude larger than those of the other matrices at the same laser fluence. The ion-to-neutral ratios predicted using the thermal proton transfer model are similar to the experimental measurements, indicating that thermal proton transfer reactions play a major role in generating ions in ultraviolet-MALDI.
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