1. Chapter 22 Mass Spectroscopy Quantitative Chemical Analysis Harris, 6th Edition

2. What is Mass Spec • Generation and Separation of Charged Molecules based on a mass to charge ratio. • Applications from Geochemistry to Biotechnology

3. Mass Definitions • Atomic Mass – Mass from periodic table based isotope abundance • Molecular Mass – Mass for the sums of the atomic masses (Water = 2*1.0079 + 15.9994 = 18.0152 Da) • Nominal Mass - Sum of integer masses of most abundant isotopes. (Water = 18 Da)

4. Typical Mass Spectrometer • Ion source - electron beam • Ion separation - magnet • Ion detection - Electron multiplier • A high vacuum method (avoid collisions that will effect ions)

6. Ionization Process • M + e- (70 eV)→ M+. + e- (~55 eV)+e- ( 0.1 eV) • Typical ionization energies are 9 to 10 eV

8. Chemical Ionization • Add a gas such as methane in greater amount. The methane in ionized and then the energy is transferred to the analyte on collision. • Much less energy passed to analyte

10. Resolution • Most application require the ability to resolve integer difference in the working range. • Some high resolution instruments are available and these can give exact molecular formula

11. Small portion of Methyl Stearate (CH3(CH2)16CO2CH3

12. Isotope patterns tell us much.

14. For interpretation

16. Quadrupole Ion Separators

17. Time of Flight

18. Quadrupole Ion Trap

19. Quadrupole Ion Trap

20. LC – MSPneumatically Assisted Electrospray

21. Gas Phase Ion Formation

22. Outlet Photograph

23. CZE – MS Interface

24. Atmospheric Pressure Chemical IonizationAPCI

25. Selected Ion Monitoring

26. Triple Quad Instruments

27. MALDI – Matrix Assisted Desorption / Ionization

28. MALDI Example

29. Electrospray of Proteins (Multiple Charges) Acidified bovine cytochrome c