Matrix-assisted laser desorption electrospray ionization (MALDESI) describes a process by which a laser is used to resonantly excite a matrix thereby facilitating the desorption of neutral analyte molecules.  These neutrals then partition into a plume of charged solvent droplets where they are ionized through an ESI-like process.  The use of an infrared laser (2.94 �m) allows liquid water or ice to be used as the matrix, however very little is known about the influence this ice layer may have on plume dynamics in an ambient environment.  Shadowgraphy and selective fluorescence techniques are used to investigate the ablation dynamics and interaction of the desorbed material with the charged droplets of the electrospray plume, while the mass spectrometer is used to simultaneously collect data so that direct correlations can be made with improvements in MALDESI signal.  One of the key features of the recently developed IR-MALDESI imaging source includes synchronization between ablation, ion accumulation, and MS acquisition to improve spot to spot reproducibility.  This imaging source has since been used for drug and metabolism studies as well as hypothesis driven and discovery based investigations to discern the dissimilarities between tissue sections from various biological states.  Along with the fundamental measurements and applications, freely available, open-source, and vendor neutral software has been developed on the MATLAB platform to process and analyze mass spectrometry imaging data.

Fundamentals and applications of the infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) source for mass spectrometry imaging

246th National Meeting (2013)

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