Recent developments in atmospheric pressure MALDI mass spectrometry

A new atmospheric pressure (AP) matrix-assisted laser desorption/ionization (MALDI) ion source that includes an extended capillary for delivery of AP-MALDI ions toward a mass spectrometer (MS) atmospheric pressure interface inlet aperture, an optical fiber for laser energy transfer to a target, and x-y travel stages for high throughput analysis of multiple samples, is described. The new source has been interfaced with a Thermo Finnigan LCQ ion trap mass spectrometer bringing powerful high throughput tandem MS capabilities to MALDI analysis. The resulting AP-MALDI-LCQ instrument demonstrated an absolute sensitivity in the low femtomole range for simple peptide mixture analysis, a mass range up to 2000-4000 (limited by LCQ), and an extensive fragmentation of singly-charged AP-MALDI ions in MS/MS experiments. The potential strength of this technique has been illustrated by numerous applications ranging from fragile molecule analysis to tryptic digest analysis for protein identification. (C) 2002 Elsevier Science B.V. All rights reserved.