LECTURE 18 MASS SPECTROMETRY ADDITIONAL TECHNIQUES SOFT IONIZATION AN INTRODUCTION

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LECTURE 18MASS SPECTROMETRY ADDITIONAL
TECHNIQUES SOFT IONIZATION AN INTRODUCTION

• WAYS TO FORM IONS
• ION MOLECULE REACTIONS
• RAPID VAPORIZATION IONIZATION
• ENERGY SUDDEN IONIZATION

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GOAL OF MS TO ID m/z PARENT ION
SOLVE THE STRUCTURE
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SOLVE THE STRUCTURE
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SOLVE THE STRUCTURE
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GOAL OF MS TO ID m/z PARENT ION
SOLVING THE PROBLEM BY COMPARING DATA FROM
DIFFERENT METHODS
CORE TECHNIQUE M
SI -1
SI -2
SI -3
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GOAL OF MS TO ID m/z PARENT ION
SOLVING THE PROBLEM BY COMPARING DATA FROM
DIFFERENT METHODS
CORE TECHNIQUE M
SI -1
SI -2
SI -3
WHAT BEST METHODS? WHAT ARE ESI, FT-ICR-MS,
MS-MS?
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FIVE WAYS TO FORM IONS

• EI _at_ 70 EV
• ION MOLECULE REACTIONS
• FIELD DESORPTION IONIZATION
• LASER DESORPTION IONIZATION
• SPRAY IONIZATION TECHNIQUES

See pg 285
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FIVE WAYS TO FORM IONS

• EI _at_ 70 EV
• ION MOLECULE REACTIONS
• FIELD DESORPTION IONIZATION
• LASER DESORPTION IONIZATION
• SPRAY IONIZATION TECHNIQUES

M OR MH ODD EVEN ION
ION
See pg 285
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ION MOL RXN
P285
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RAPID VAPORIZATION FAB FAST
ATOM BOMBARDMENT IONIZATION LDI LASER DESORPTION
IONIZATION MALDI MATRIX ASSISTED LASER
DESORPTION IONIZATION
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P285
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ENERGY SUDDEN (STRONG ELECTRIC FIELD) FD FIELD
DESORPTION FI FIELD IONIZATION ESI ELECTROSPRAY
IONIZATION
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P285
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WHAT FORMULA? WHAT STRUCTURE?
M MH
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WHAT FORMULA? WHAT STRUCTURE?
M MH
131
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WHAT FORMULA? WHAT STRUCTURE?
M MH
C6H10O 98
O2130 ON128 H10
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WHAT FORMULA? WHAT STRUCTURE?
M MH
C6H10O 98
O2130 ON128 H10
131-(130) 1 ? C6H11O3 or 131-128 3 ? C6H13O2N
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WHAT FORMULA? WHAT STRUCTURE?
M MH
- 45 CO2H
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ESI A POPULAR METHOD
POS
C36H44N4O MW 548
C28H48SO10 MW 576
NEG
14 POSSIBLE FORMULAS
M- - H1O3
P296
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SUMMARY

• Some (of the five) ways to form ions (a) ion
  mole rxn, (b) spray ionization, (c) laser
  desorption ionization.
• Remember to consider both positive ion and
  negative ion formation.
• Soft ionization by Spray Ionization (ESI) or by
  Ion Molecule Reaction (CI) is now in vogue!
• Remember to look for MH rather than M
• Soft ionization helps to focus attention on the
  molecular ion cluster.
• Other techniques MS-MS, FT-ICR-MS lets
  discuss these later.