High mass-resolution MS imaging using JMS-S3000 "SpiralTOF™" and statistical data analysis
MSTips No. 370
Imaging mass spectrometry (MSI) using matrix-assisted laser desorption/ionization (MALDI) is a technique for visualizing the distribution of organic compounds on a sample surface. Applications are being expanded mainly for proteins, peptides, lipids, drugs, and their metabolites on the surface of frozen tissue sections. MALDI-MSI scans the laser irradiation position two-dimensionally on the sample surface and acquires a mass spectrum at each laser irradiation position. By analyzing this series of mass spectra with two-dimensional positional information, the distribution of organic compounds with arbitrary molecular weights on the sample surface can be drawn as an extracted mass image.
The JMS-S3000 SpiralTOF™ is a time-of-flight mass spectrometer (TOFMS) with patented spiral trajectory ion optics. Because it has a flight distance of 17 m, which is longer than ordinary reflectron TOFMS, high mass resolution can be achieved even in MSI, where the surface condition of the sample is often uneven. In addition, the ion optical system is composed of sector electric fields, which makes it possible to remove post-source decay (PSD) ions, and it is also possible to detect trace components near the baseline with high mass resolution. Therefore, even in MALDI-MSI, it is possible to separate compounds with the same nominal mass but different exact masses (isobars) and draw a clear distribution of the compounds. In this report, we report the statistical analysis of high-mass resolution MALDI-MSI data of various lipids in biological samples.