Mass Analyzers Double Focusing Magnetic Sector Quadrupole Mass Filter Quadrupole Ion Trap Linear...

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Transcript of Mass Analyzers Double Focusing Magnetic Sector Quadrupole Mass Filter Quadrupole Ion Trap Linear...

  • Slide 1
  • Mass Analyzers Double Focusing Magnetic Sector Quadrupole Mass Filter Quadrupole Ion Trap Linear Time-of-Flight (TOF) Reflectron TOF Fourier Transform Ion Cyclotron Resonance (FT-ICR-MS)
  • Slide 2
  • Mass Analyzers Resolution R = m / m Accuracy/Precision mass measurement accuracy/reproducibility Transmission % of ions allowed through the analyzer Mass Range Highest m/z that can be analyzed Scan Speed How many spectra per unit of time
  • Slide 3
  • Effect of Increased Resolution Gastric Inhibitory Peptide C 225 H 341 N 59 O 66 S MW: 4957 Pulmonary Surfactant C 917 H 1473 N 235 O 268 S 11 MW: 20417 Spectroscopy 2004, 19, 34-40.
  • Slide 4
  • Double-Focusing Magnetic Sector
  • Slide 5
  • Double-Focusing Magnetic Sector Magnetic Sector mqmq r 2 B 2 2V = B = magnetic field strength r = radius of curvature in magnetic field V = accelerating voltage m = ion mass q = ion charge All ions of the same m/z will have the same radius Only if the Ion kinetic energy is constant
  • Slide 6
  • Double-Focusing Magnetic Sector Electric Sector r 2E k qE = E k = ion kinetic energy r = radius of curvature in electric field E = magnitude of electric field q = ion charge All ions exiting the electric sector have the same kinetic energy
  • Slide 7
  • Magnetic Sector Typically a voltage of 5-10kV is used to accelerate ions To obtain a full spectrum, magnetic field is scanned To obtain a HR scan, voltage is scanned at constant magnetic field To gain maximum sensitivity at one mass SIM scan is done B and E are constant for one or more masses
  • Slide 8
  • Quadrupole Mass Filter http://www.asms.org
  • Slide 9
  • Quadrupole E = U - Vcos(2t) E = potential applied to the rods U = DC potential V = RF amplitude = RF frequency t = time Quadrupole is scanned at a constant U/V
  • Slide 10
  • Quadrupole Typically U varies from 500-2000 V V varies from 0 - 3000V (-3000 to +3000) Scanning U/V at a fixed ratio gives a full scan Higher values of U/V give higher resolution RF only (U=0) transmits all ions Higher sensitivity through SIM scan Jumping to specific points on the U/V line
  • Slide 11
  • MS/MS with multiple quadrupoles 1.Product ion scan ESI and/or LC-MS 2. Precursor ion scan EI or CI and GC-MS 3. Neutral loss scan EI and CI http://www.chm.bris.ac.uk/ms/theory/tandem-ms.html
  • Slide 12
  • Quadrupole Ion Trap Ions are injected into the trap and all ions are trapped RF and DC are scanned to sequentially eject ions for detection Specific ions can be trapped while others are ejected Ion velocity can be increased to induced fragmentation
  • Slide 13
  • Quadrupole Ion Trap http://www.chm.bris.ac.uk/ms/theory/qit-massspec.html
  • Slide 14
  • Time-of-Flight (TOF) mv 2 2 zV s = E k = kinetic energy v = ion velocity d = flight distance t = flight time V s = accelerating voltage m = ion mass q = ion charge All ions of the same m/z will have the same flight time Only if the Ion kinetic energy is constant = EkEk dtdt = vt 2 = mzmz d 2 2V s
  • Slide 15
  • TOF Ions are accelerated with 5-35 kV Space focusing of source ions is accomplished by delayed extraction An electrostatic analyzer (reflectron) is used correct for kinetic energy spread
  • Slide 16
  • Reflectron Time-of-Flight http://www.chm.bris.ac.uk/ms/theory/tof-massspec.html
  • Slide 17
  • Reflectron Time-of-Flight (ESI-TOF) Courtesy Bruker Datonics BioTOF users Manual
  • Slide 18
  • FT-ICR-MS v 2r f = B = magnetic field strength v = ion velocity f = orbital frequency m = ion mass q = ion charge r= orbital radius At constant B, orbital frequency is inversely related to m/z Frequency is independent of kinetic energy qvB = mv 2 r vrvr 2f = = qB 2m Centripital Force Circular Path r and v drop out
  • Slide 19
  • FT-ICR-MS Ions are all trapped radially by a magnetic field (typically 3-15 T) Axial trapping by DC potential Ion radius is increased by RF pulse also brings orbits into phase Orbiting ions induce RF current in receiver plates Image current is a composite of all frequences in time domain FFT gives frequency (mass) spectrum
  • Slide 20
  • FT-ICR-MS
  • Slide 21
  • 1200140016001800m/z m = 0.01933 a.u. 1/m = 51.7308 a.u. mass = 64428 a.u. 1278.31278.8m/z 52+ 52+ 60+ 36+ Electrospray: Broadband Spectrum of Bovine Serum Albumin (66kDa) 7.0T Actively Shielded Magnet
  • Slide 22
  • FT-ICR-MS Electrospray: Deconvoluted Spectrum of Bovine Serum Albumin (66kDa) 7.0T Actively Shielded Magnet 664106643066450m/z m = 1.004 a.u.
  • Slide 23
  • Mass Analyzers: Performance and Price Spectroscopy 2004, 19, 34-40.
  • Slide 24
  • Ion Detectors Electron Multiplier http://www.chm.bris.ac.uk/ms/theory/detection.html
  • Slide 25
  • Ion Detectors http://www.chm.bris.ac.uk/ms/theory/detection.html
  • Slide 26
  • MS for Chemical Imaging TOF-SIMS imaging +
  • Slide 27
  • cold stage extraction lens extraction lens blanking aperture secondary ions retard reflect reflectron detector Primary Ion Source Tof SIMS Imaging Courtesy of Mike Kurczy, Winograd Group, Penn State University
  • Slide 28
  • MASS SPEC IMAGING Courtesy of Mike Kurczy, Winograd Group, Penn State University
  • Slide 29
  • Application of TOF-SIMS imaging to biology Membrane lipid heterogeneity during tetrahymena mating
  • Slide 30
  • Science 2004, 305, 71
  • Slide 31
  • Membrane lipid heterogeneity during tetrahymena mating m/z = 69m/z = 184 Science 2004, 305, 71
  • Slide 32
  • Membrane lipid heterogeneity during tetrahymena mating PC is depleted in mating region What lipid is enriched? Should be cone shaped Science 2004, 305, 71
  • Slide 33
  • Membrane lipid heterogeneity during tetrahymena mating m/z = 126 Science 2004, 305, 71
  • Slide 34
  • Membrane lipid heterogeneity during tetrahymena mating Science 2004, 305, 71