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High Mass Resolution MALDI-MS Imaging Part II: Using the "MALDIVision" from PREMIER Biosoft

Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MS Imaging) is a powerful tool for the biochemical analyses of surfaces. Previously, this technique has been used to determine the spatial distribution of hundreds of unknown compounds in thinly sliced tissue sections. The mass spectral images are generated by changing the laser irradiation point at regular intervals across the sample surface and collecting a mass spectrum for each point. Time-of-flight mass spectrometers (TOFMS) are widely used as the mass analyzer for MALDI-MS Imaging because they are well matched for the MALDI ionization process. Ultra-high mass resolution achieving isobaric peak separation is important for lipid profiling using MALDI-Imaging [1, 2]. However, the fine structure of the matrix crystals and small irregularities in the tissue surface flatness can cause peak drift in the collected mass spectra that is caused by slight differences in the starting point of the flight path for the ions at each laser irradiation point. As a result, the typical reflectron type TOFMS systems have a difficult time achieving high mass resolution from spot to spot over a thinly sliced biological surface.

High Mass Resolution MALDI-imaging MS Using JMS-S3000 SpiralTOF and msMicroImager

Imaging mass spectrometry using matrix-assisted laser desorption/ionization mass spectrometry (MALDI-Imaging) has been expanded during the last decade in biological applications, to assess the distribution of proteins, peptides, lipids, drugs, and metabolites in a tissue specimen. In MALDI-Imaging measurements, a laser irradiation point was scanned on a sample surface to acquire a mass spectrum at each point. Analyzing the mass spectra with two-dimensional position information, localization of compounds with inherent molecular weights can be visualized or the mass spectra for certain regions of interests (ROIs) can be created. The JMS-S3000 SpiralTOF (Fig. 1) is a MALDI-TOFMS, which utilizes the JEOL patented spiral ion optical 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). On the other hand, there are some issues for analyzing high mass resolution and high lateral resolution MALDI-Imaging raw data with common imaging software options such as Biomap.

High Mass Resolution MALDI-Imaging MS: High Stability of Peak Position during Imaging MS Measurement

Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI-Imaging MS) is a powerful tool for the biochemical analyses of surfaces. Previously, this technique has been used to determine the spatial distribution of hundreds of unknown compounds in thinly sliced tissue sections. The mass spectral images are generated by changing the laser irradiation point at regular intervals across the sample surface and collecting a mass spectrum for each point. Time-of-flight mass spectrometers (TOFMS) are widely used as the mass analyzer for MALDI-Imaging MS because they are well matched for the MALDI ionization process. However, the fine structure of the matrix crystals and small irregularities in the tissue surface flatness can cause peak drift in the collected mass spectra that is caused by slight differences in the starting point of the flight path for the ions at each laser irradiation point. As a result, the typical reflectron type TOFMS systems have a difficult time achieving high mass resolution from spot to spot over a thinly sliced biological surface. Conversely, the JEOL JMS-S3000 “SpiralTOFTM”, which has 5-10 times longer flight path than the reflectron type TOF, is able to reduce the effect of this mass drift to achieve high mass resolution and high mass accuracy. In this work, we report the advantages of using the SpiralTOF for MALDI-Imaging MS analyses of lipids in a mouse brain tissue section.

Gunshot Residues (GSR) Analysis by Using MALDI Imaging

Recently, matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) imaging techniques have been developed for biological sciences to evaluate and understand the distribution of various chemicals on biological surfaces. In particular, this technique provides useful visual information about the locations of specific chemicals on surfaces. In this work, we explored the use of MALDI-MS imaging for the forensically applicable sample of gunshot residues (GSR). These measurements were done using a spiral-trajectory ion optics time-of-flight mass spectrometer (SpiralTOF-MS) which has a 17m flight path that provides high resolution capabilities, even down into the lower m/z region. Additionally, the m/z axis remains very stable over the long time period required for MALDI-MS imaging.

Gold Star Mothers Stamp - Analysis Using Scanning Electron Microscopy and Mass Spectrometry

Since 1949, the JEOL legacy has been one of outstanding innovation in developing instruments used to advance scientific research and technology. JEOL has over 60 years of expertise in the field of electron microscopy, more than 50 years in mass spectrometry. In this applications note, we performed an analysis of a Gold Star Mothers Postage Stamp by using three JEOL instruments. We used the JSM-IT300LV which the latest addition to JEOL‘s popular series of analytical low vacuum SEM, , the JMS-T100LP “AccuTOF- DART” the first commercially available ambient ionization mass spectrometer, and the JMS-S3000 “SpiralTOF” which has highest mass-resolution and mass accuracy of all commercially available MALDI-TOFMS systems. We can therefore correlate analyses from various analytical techniques on the same sample.

Fingerprint Analyses Using MALDI Imaging and SEM Imaging

MALDI imaging is a state-of-art mass spectrometry technique that allows for the visualization of chemical distributions on the surfaces of biological and material samples. This analytical technique can provide the chemical distribution on the surface as an image that is mapped using the intensity of the observed ions. The image contains individual MALDI mass spectra at each pixel. Therefore, it is possible to simultaneously carry out high-mass-resolution qualitative analysis and chemical distribution analysis. The JMS-S3000 SpiralTOF (Figure 1) has a unique 17m fl ight path that offers the highest mass resolution and mass accuracy MALDI-TOF MS system. In this work, we demonstrated the MALDI imaging measurement for the fi ngerprints of a smoker and a non-smoker by using the JEOL SpiralTOF system. Additionally, we looked at the smoker’s fi ngerprint using the JEOL JSM-7800F thermal fi eld emission scanning electron microscope (FE-SEM) shown in Figure 2.

Ballpoint Ink Analyses Using LDI Imaging and SEM/EDS Techniques

Recently, matrix assisted laser desorption/ionization (MALDI) imaging techniques have been developed for biological sciences to evaluate and understand the distribution of various chemicals on biological surfaces. In particular, this technique provides useful visual information about the locations of specific chemicals on surfaces. In this work, we explored the use of laser desorption/ionization (LDI) imaging for forensically applicable samples such as a handwriting sample with a ballpoint ink. These measurements were done using a spiral-trajectory ion optics time-of-flight mass spectrometer (SpiralTOF-MS). This TOF system has a 17m flight path that provides high resolution capabilities even down into the lower m/z region. Additionally, we looked at the SEM/EDS imaging using the JEOL JSM-6510LV scanning electron microscope.

Analysis of organic compounds on an acrylic plate using JMS-S3000 SpiralTOF™ - MSTips - 251

Industrial materials are often evaluated by surface analysis instruments that provide information on surface elements, bonding states, and functional groups. However, there are limited options for surface analysis techniques that provide molecular weight and molecular structure information for organic compounds present on surfaces. Matrix Assisted Laser Desorption Ionization - Time of Flight Mass Spectrometry (MALDI-TOFMS) is a soft ionization technique that can be used to analyze surfaces in order to estimate elemental compositions with accurate mass measurements, obtain structural information by using MS/MS, and map surface compounds by using MS imaging. MALDI-TOFMS uses a high voltage on the target plate to accelerate the ions into the TOFMS analyzer. Therefore, the target plates are conductive and are typically made of stainless steel. MALDI imaging mass spectrometry is widely used for analyzing organic substances on frozen tissue sections. In this case, a frozen tissue section with a thickness of about 10 μm is placed on a conductive glass slide coated with an indium tin oxide (ITO) film. However, for the analysis of industrial products, the target organic compounds are on nonconductive substrates such as resins with millimeter thicknesses. MALDI-TOFMS surface measurements using nonconductive substrates lead to a reduction in mass resolution and a significant decrease in ion intensity due to surface charging. This problem can be solved by pretreating the surface with gold vapor deposition in order to change it from nonconductive to conductive. This method was previously shown to work well in MSTips No. 204 in which the gold vapor deposition method was applied to the MALDI-MS imaging analysis of inks on paper. In this report, we used gold vapor deposition to look at samples on the surface of a 1 mm thick acrylic plate.

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Corona - Glow Discharge (DART Ion Source)

February 22, 2020
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