Atmospheric pressure matrix-assisted laser desorption/ionization with analysis by ion mobility time-of-flight mass spectrometry

The use of an atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) source was employed with an atmospheric pressure ion mobility spectrometer (APIMS) and an orthogonal acceleration reflector time-of-flight mass spectrometer (TOFMS) to analyze dipeptide and biogenic amine mixtures from a liquid glycerol 2,5-dihydroxybenzoic acid (DHB) matrix. Improved sensitivities were obtained by the addition of a localized electrical (corona) discharge in conjunction with the AP-MALDI source. Enhanced sample ionization efficiency created by this combination provided an overall elevation in signal intensity of similar to1.3 orders in magnitude. Combinations of three dipeptides (Gly-Lys, Ala-Lys, and Val-Lys) and nine biogenic amines (dopamine, serotonin, B-phenylethylamine, tyramine, octopamine, histamine, tryptamine, spermidine, and spermine) were resolved in less than 18 ms. In many cases, reduced mobility constants (K-o) were determined for these analytes for the first time. Ion mobility drift times, flight times, arbitrary signal intensities, and collision-induced dissociation (CID) fragmentation product signatures are reported for each of the samples. Copyright (C) 2004 John Wiley Sons, Ltd.