Infrared Matrix-Assisted Laser Desorption Electrospray Ionization (IR-MALDESI) Imaging Source Coupled to a FT-ICR Mass Spectrometer

TLDR

Mass spectrometry imaging monitors chemical abundance and spatial distribution on tissue surfaces, and its development over the past 15 years has expanded applications, especially with ambient‑pressure ionization sources that require minimal sample preparation. The authors present a versatile MALDESI imaging source coupled to a hybrid LTQ‑FT‑ICR mass spectrometer. The source enables single‑shot or multi‑shot acquisition per pixel, with full control over laser repetition rate and the mass spectrometer’s scanning cycle, and is integrated with a commercial FT‑ICR instrument. Scanning rates of up to one pixel per second and a spatial resolution of 45 µm were achieved using oversampling.

Abstract

Mass spectrometry imaging (MSI) allows for the direct monitoring of the abundance and spatial distribution of chemical compounds over the surface of a tissue sample. This technology has opened the field of mass spectrometry to numerous innovative applications over the past 15 years. First used with SIMS and MALDI MS that operate under vacuum, interest has grown for mass spectrometry ionization sources that allow for effective imaging but where the analysis can be performed at ambient pressure with minimal or no sample preparation. We introduce here a versatile source for MALDESI imaging analysis coupled to a hybrid LTQ-FT-ICR mass spectrometer. The imaging source offers single shot or multi-shot capability per pixel with full control over the laser repetition rate and mass spectrometer scanning cycle. Scanning rates can be as fast as 1 pixel/second and a spatial resolution of 45 μm was achieved with oversampling. Design and integration of a versatile IR-MALDESI imaging source offering multi-shot capability with a commercial FT-ICR mass spectrometer.