1. Mass spectrometry
Detection of ionic species to determine the molecular weight of and obtain structural information on a molecule

2. Mass spectrometry

3. ions only detected
individual molecules are detected
uses isotopic masses not MW

4. 29
Base peak
Parent ion
Base Peak
Parent ion
-15
-CH3

5. 43 58 29 44
Acetone
Acetaldehyde
-15
-CH3
-15
-CH3

6. Isotope effects Molecular weight Br = 79.9040 Br isotopic abundance
CH379Br
CH381Br

7. Isotope effects Molecular weight Br = 79.9040 Br isotopic abundance
CH379Br
CH381Br

8. Isotope effects Molecular weight Cl = 35.453 Cl isotopic abundance
35Cl : 37Cl Ratio = 3:1
CH335Cl
CH337Cl

9. MS Ionization Techniques
High energy
hard ionization
Low energy
soft ionization
Electron Impact (EI) uses beam of electrons
Fast Atom Bombardment (FAB) uses beam of atoms
Chemical Ionization (CI) uses chemical reactions
Matrix Assisted Laser Desorption (MALDI) uses lasers to ionize molecules
Electrospray uses compounds which are already ionic