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Mass Spectrometry

Mass Spectrometry. Instrumentation: Ionization methods and analyzers. Parts of an MS. Ionization Methods. EI CI FD FAB MALDI ES. EI (and CI). EI vs CI. FD. http://en.wikipedia.org/wiki/Field_desorption

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Mass Spectrometry

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  1. Mass Spectrometry Instrumentation: Ionization methods and analyzers

  2. Parts of an MS

  3. Ionization Methods EI CI FD FAB MALDI ES

  4. EI (and CI)

  5. EI vs CI

  6. FD • http://en.wikipedia.org/wiki/Field_desorption • High voltage applied to metal emitter with carbon microneedles (after sample applied)

  7. EI vs CI vs FD

  8. FAB (LSIMS is similar) • http://www.chm.bris.ac.uk/ms/newversion/fablsims-ionisation.htm • Fast particle beam (Ar or Ne or Cs) impinged on sample in a matrix. Analyte ions are ejected from the surface.

  9. FAB HRMS MW = 378.08

  10. MALDI • http://www.magnet.fsu.edu/education/tutorials/tools/ionization_maldi.html • Sample in a matrix (e.g., nicotinic acid) that absorbs light is zapped with a laser beam of corresponding wavelength. The photoexcited matrix ejects analyteions from the surface.

  11. ES (or ESI) Sample in solution at atmospheric pressure forms small droplets which move toward analyzer and become smaller as solvent evaporates. Eventually they become too small and explode releasing individual analyte ions in solution.

  12. ESI vs EI

  13. ESI of a protein

  14. Summary

  15. Analyzers • Magnetic Sector • Quadrupole • Ion Trap • TOF • FT

  16. Magnetic Sector

  17. Magnetic Sector K.E. = zV = mv2/2 Deflecting force = Bzv Radius of path (r): Bzv= mv2/r m/z = B2r2/2V

  18. Quadrupole

  19. Ion Trap

  20. TOF • K.E. = zV= mv2/2 • All ions have same energy at start of “drift tube” so velocities are different: • v = (2zV/m)1/2 • Tube length = L • Time of flight (t) = (L2m/2zV)1/2

  21. Summary of Analyzers

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