1 / 13

Ionization and Mass Analyzers

Ionization and Mass Analyzers. Ionizations Electron Ionization - “hard” Chemical Ionization - “soft” MALDI - desorption FAB - desorption Laser Post Ionization - increase signal! Ion Bombardment (SIMS) - soft or hard Depends on ion fluence Mass Analyzers Analyze all mass/charge

tarala
Télécharger la présentation

Ionization and Mass Analyzers

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Ionization and Mass Analyzers • Ionizations • Electron Ionization - “hard” • Chemical Ionization - “soft” • MALDI - desorption • FAB - desorption • Laser Post Ionization - increase signal! • Ion Bombardment (SIMS) - soft or hard • Depends on ion fluence • Mass Analyzers • Analyze all mass/charge • Time-of-flight • Pre- Select Ions • Quadropole • Magnetic or Electric Sectors

  2. Electron Ionization • Molecule + e- molecule+ + 2e- • Four electromagnetic poles • Rapidly oscillating field • If mass of ion and frequency of oscillation are comparable then the ion will oscillate towards the detector and be measured • A certain mass range can be selected depending on the pole diameter Quadropole Mass Analyzer

  3. mass separate focus Electrostatic and Magnetic Sectors B = strength of magnetic field V = ion accelerating voltage r = radius of ion curvature m = mass of ion z = charge of ion M = 1-50 (change by changing B) http://www.cea.com/cai/simsinst/m_anal.htm

  4. 20 particles 10 ion - + e- Secondary Ion Mass Spectrometry “Ionization” Ga+ Static SIMS = < 1 x 1013 ions/cm2

  5. Time-of-Flight Analyzer d -V +V M+ MCP detector Field Free Region Sample e = charge on an electron 1.6 x 10-19 C t = time for ion to reach detector m = mass v = velocity V = stage voltage d = length of field free region V = voltage of detector

  6. TOF-SIMS Instrument

  7. Laser Postionization (LPI) Laser Beam Postionization parameters: 800 nm, 150 fs laser pulses, 8.5 x 1012 W/cm2 power density

  8. TOF-SIMS Molecule-Specific Imaging total ion image Ag+ Intensity Ion Gun y x 570 µm x 570 µm m/z, +ions molecule-specific image Si+ Ag+ Cu+ Si+ Cu+ copper grid affixed to silicon substrate with silver paste

  9. TOF-SIMS Identification of Plasma Membrane Lipids * - * +2H m/z 552 m/z 142 + cholesterol m/z 369 m/z 385 (M-H)+ DPPE – dipalmitoylphosphatidylethanolamine m/z 682 (M+H)+

  10. Are there Lipid Domains in the Inner Leaflet of the Membrane? cholesterol DPPE Cholesterol DPPE + 552 Total Ion DPPE/Cholesterol 250 µm x 250 µm Intensity Au - A. G. Sostarecz; C. M. McQuaw et. al. J. Am. Chem. Soc.2004. C. M. McQuaw; A. G. Sostarecz et. al. Langmuir2005.

  11. Multi-Isotope Imaging Mass Spectrometry Atomic Mass Images 14N nucleus lamellipodia endothelial cell Image from Claude Lechene Harvard Medical School

  12. mass separate focus 20 particles 10 ion - + e- MIMS is a Secondary Ion Mass Spectrometry Technique B = strength of magnetic field V = ion accelerating voltage r = radius of ion curvature m = mass of ion z = charge of ion M = 1-50 (change by changing B) http://www.cea.com/cai/simsinst/m_anal.htm

  13. MIMS uses an Electrostatic and Magnetic Sector Mass Analyzer mass separate focus 14N ion 1 84 % 16 % Image from Claude Lechene *** MIMS analysis is performed as a collaborative project with Dr. Claude Lechene at the National Resource for Imaging Mass Spectrometry at Harvard Medical School

More Related