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Mass spectrometry. Detection of ionic species to determine the molecular weight of and obtain structural information on a molecule. Mass spectrometry. ions only detected individual molecules are detected uses isotopic masses not MW. 29. Base Peak. Parent ion. -15. Base peak
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Massspectrometry Detection of ionic species to determine the molecular weight of and obtain structural information on a molecule
ions only detected • individual molecules are detected • uses isotopic masses not MW
29 Base Peak Parent ion -15 Base peak Parent ion -CH3
Acetone 43 58 -15 Acetaldehyde 29 44 -15 -CH3 -CH3
Isotope effects Molecular weight Br = 79.9040 Br isotopic abundance 79Br = 50.5 % 81Br = 49.5 % CH379Br CH381Br
Isotope effects Molecular weight Br = 79.9040 Br isotopic abundance 79Br = 50.5 % 81Br = 49.5 % CH379Br CH381Br
Isotope effects Molecular weight Cl = 35.453 Cl isotopic abundance 35Cl = 75.4 % 37Cl = 24.6 % 35Cl : 37Cl Ratio = 3:1 CH335Cl CH337Cl
High energy hard ionization Low energy soft ionization MS Ionization Techniques • 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 • Electrosprayuses compounds which are already ionic