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Mass Spectrometry Imaging (MSI) on mixed conductive/non-conductive substrate using JMS-S3000 SpiralTOF™ - MSTips - 288

In the industrial field, there is interest in measuring organic compounds on non-conductive substrates, such as resins a few millimeters thick. If the mass spectrum is obtained from the non-conductive surface with no pre-treatment, the mass resolution will be lower, and ultimately the ion intensity will decrease significantly due to the charge-up effect. This issue can be solved by providing conductivity to the non-conductive part via the gold deposition method.[1] In this report, MSI is performed using a permanent red marker on a substrate with a conductive part and a non-conductive part. Previously, ions could be observed only from the conductive part. Now, with the gold deposition method, they can be observed from both the conductive and the non-conductive parts, and they can be properly mapped.

MALDI-Imaging MS of Lipids on Mouse Brain Tissue Sections Using Negative Ion Mode

The main biological functions of lipids include energy storage, signaling, and acting as structural components of cell membranes. Not only their chemical composition and structures but also the distributions in biological body are important for biochemistry. Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-Imaging MS) is a powerful tool for the biochemical analyses of surfaces. Different lipid types are observed in positive or negative-ion MALDI mass spectra, depending on the presence of polar functional groups. Phosphatidyl cholines and galactosyl ceramides were mainly observed in the MALDI-Imaging MS of positive ion mode using JMS-S3000 SpiralTOF[1]. In this work, we report the use of the SpiralTOF for negative-ion MALDI-Imaging MS of sulfatides. High-resolution, accurate mass data and MS/MS data obtained under high-energy CID conditions provide information about structures, elemental compositions, and localization of many types of sulfatides.

MALDI Imaging and Structural Analysis of Lipids Directly on Tissue Specimens

In this paper, we report the use of mass spectrometry imaging and structural analysis of lipids directly on a tissue specimen, carried out by means of matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry, using a combination of spiral orbit-type and reflectron-type time-of-flight mass spectrometers. The most intense peak observed in the mass spectrum from a brain tissue specimen was confirmed as phosphatidylcholine (34 : 1) [M+K]+, using tandem mass spectrometry. The charge remote fragmentation channels, which are characteristically observed using high-energy collision induced dissociation, contributed significantly to this confirmation. Accurate mass analysis was further facilitated by mass correction using the confirmed peak. In mass spectrometry imaging, the high resolving power of our system could separate doublet peak of less than 0.1 u diveerence, which would otherwise be problematic when using a low-resolution reflectron type time-of-flight mass spectrometer. Two compounds, observed at m/z 848.56 and 848.65, were found to be located in complementary positions on a brain tissue specimen. These results demonstrate the importance of a high-performance tandem time-of-flight mass spectrometer for mass spectrometry imaging and analysis of observed compounds, to allow distinction between biological molecules.

High Mass-Resolution MALDI-imaging MS for Drug Metabolism in Tissue Using the JMS-S3000

The JMS-S3000 SpiralTOF is a MALDI-TOFMS, which utilizes the JEOL patented spiral ion optics system. It has a 5-10 times longer flight path than the typical reflectron type MALDI-TOFMS. As a result, it can achieve high mass-resolution to separate peaks that have the same nominal mass but have different exact masses (isobaric separation). This feature is particularly effective for MALDI-Imaging for drug metabolism, which typically consist of relatively low molecular weight compounds which are often interfered with by matrix compounds and/or surface contaminants.

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Corona - Glow Discharge (DART Ion Source)

February 22, 2020
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