Visualization of Volatile Substances in Different Organelles with an Atmospheric-Pressure Mass Microscope

Abstract

We have developed a mass microscope (mass spectrometry imager with spatial resolution higher than the naked eye) equipped with an atmospheric pressure ion-source chamber for laser desorption/ionization (AP-LDI) and a quadrupole ion trap time-of-flight (QIT-TOF) analyzer. The optical microscope combined with the mass spectrometer permitted us to precisely determine the relevant tissue region prior to performing imaging mass spectrometry (IMS). An ultraviolet laser tightly focused with a triplet lens was used to achieve high spatial resolution. An atmospheric pressure ion-source chamber enables us to analyze fresh samples with minimal loss of intrinsic water or volatile compounds. Mass-microscopic AP-LDI imaging of freshly cut ginger rhizome sections revealed that 6-gingerol ([M + K](+)at m/z 333.15, positive mode; [M - H](-) at m/z 293.17, negative mode) and the monoterpene ([M + K](+) at m/z 191.09), which are the compounds related to pungency and flavor, respectively, were localized in oil drop-containing organelles. AP-LDI-tandem MS/MS analyses were applied to compare authentic signals from freshly cut ginger directly with the standard reagent. Thus, our atmosphere-imaging mass spectrometer enabled us to monitor a quality of plants at the organelle level.

Salamander retina phospholipids and their localization by MALDI imaging mass spectrometry at cellular size resolution

“…AP MALDI IMS data were acquired using a Mass Microscope ( 22 ). The Mass Microscope was developed by combining a LC-MS-IT-TOF (Shimadzu Corp., Kyoto, Japan) with a newly scanning AP MALDI system.…”

Small molecule-sensing strategy and techniques for understanding the functionality of green tea

“…5) To overcome the limitation of the 1,5-DAN-MALDI-MSI technique and to ensure its practical use, further improvement of its detection sensitivity, such as employing a targeted selective reaction monitoring mode (SRM) approach using a triple quadrupole system (QqQ), 89) application of a Fourier transform ion cyclotron resonance-MS (FT-ICR-MS) instrument capable of accumulating continuously selected ions, 90) and on-tissue chemical derivatization approaches to increase the ionization efficiency 91,92) as well as the improvement of MALDI efficiency based on matrix choice and development, may be required. Additionally, other studies including kinetic histochemistry, 80,84,93) microscopic analysis with high-spatial resolution, [94][95][96] 3D imaging, [97][98][99] , and distribution of other metabolites 86,99) will be required to unravel both the biological consequences of biotransformation of the dietary polyphenol and its mechanism (s) of action. …”

Application of Matrix-Assisted Laser Desorption/Ionization Imaging Mass Spectrometry

“…The limitation of the scan pitch, which decides the spatial resolution of the image, depends on the laser spot size and mechanical movement control of the mass spectrometer sample stage. We have developed a new instrument (Mass Microscope) that can move the sample stage by 1 μm, and in which the finest size of the laser diameter is approximately 10 μm (Harada et al, 2009). The measurement time depends on the number of data spots, the frequency of the laser, the number of shots per spot, and the time required to move the sample stage.…”