Related Experiment Video
Updated: Jun 13, 2026

Atmospheric-pressure Molecular Imaging of Biological Tissues and Biofilms by LAESI Mass Spectrometry
Published on: September 3, 2010
Laserspray ionization on a commercial atmospheric pressure-MALDI mass spectrometer ion source: selecting singly or
Charles N McEwen1, Barbara S Larsen, Sarah Trimpin
1Department of Chemistry and Biochemistry, University of the Sciences in Philadelphia, Philadelphia, Pennsylvania 19104, USA.
Abstract:
Multiply charged ions, similar to those obtained with electrospray ionization, are produced at atmospheric pressure (AP) using standard MALDI conditions of laser fluence and reflective geometry. Further, the charge state can be switched to singly charged ions nearly instantaneously by changing the voltage applied to the MALDI target plate. Under normal AP-MALDI operating conditions in which a voltage is applied to the target plate, primarily singly charged ions are observed, but at or near zero volts, highly charged ions are observed for peptides and proteins. Thus, switching between singly and multiply charged ions requires only manipulation of a single voltage. As in ESI, multiple charging, produced using the AP-MALDI source, allows compounds with molecular weights beyond the mass-to-charge limit of the mass spectrometer to be observed and improves the fragmentation relative to singly charged ions.
More Related Videos
10:47Whole-body Mass Spectrometry Imaging by Infrared Matrix-assisted Laser Desorption Electrospray Ionization (IR-MALDESI)
Published on: March 24, 2016
09:38Dithranol as a Matrix for Matrix Assisted Laser Desorption/Ionization Imaging on a Fourier Transform Ion Cyclotron Resonance Mass Spectrometer
Published on: November 26, 2013
Related Concept Videos
Matrix-Assisted Laser Desorption Ionization (MALDI)
MALDI-TOF Mass Spectrometry
Electrospray Ionization (ESI) Mass Spectrometry
ESI utilizes electrical energy to transfer ions from the liquid phase of the sample into the...
Inductively Coupled Plasma–Mass Spectrometry (ICP–MS): Overview
Mass Spectrometers
Mass Spectrum: Interpretation