Faster raster matrix-assisted laser desorption/ionization mass spectrometry imaging of lipids at high lateral resolution

Abstract

The clinical use of mass spectrometry imaging (MSI) is rapidly growing, and applications are expanding. Crucially, the analysis of clinical cohorts requires a combination of higher analytical throughput and higher lateral resolution. Here, we demonstrate the benefits of an improved design of a prototype MALDI source (referred as “uMALDI”) mounted on a SYNAPT HDMS G2-Si mass spectrometer – widely used by the MSI community. The uMALDI source allows for imaging of lipids on histologically well documented rat brain sections at a lateral resolution of 15 μm without oversampling. We also investigate the fast rastering capabilities of the platform enabled by a new web-based MS control program (i.e. “WREnS” Waters Research Enabled Software). The combination of the uMALDI and WREnS allows high spatial resolution images at acquisition rates up to 20 pixels per second. Additionally, we demonstrate the capability of this platform to characterize the lipid distribution of osteoarthritic (OA) cartilage at the cellular level, which highlights potential benefit for broader application in clinical context. Finally, we prove that ion mobility separation of isobaric lipid species is maintained and images can be acquired at a rate of 10 scans per seconds. This renders a unique ion mobility mass spectrometric imaging platform with high acquisition rates and high spatial resolution.