Daniel C. Harris Quantitative Chemical Analysis Seventh Edition Chapter 22 Mass spectrometry Copyright © 2007 by W. H. Freeman and Company What is mass 28? •N2 •CO •C2H4 (ethylene) •H6B2 (diborane) http://webbook.nist.gov/chemistry/mw-ser.html 1 Instrumentation Instrumentation 2. Mass selection: 3 step program: • Magnetic sector • Quadrupole 1.Ionize • Time-of-flight (TOF) 2.Mass select • Ion trap 3.detect • Fourier transform ion cyclotron resonance • Ion Mobility NB: REQUIRE VACUUM CHAMBER Instrumentation – magnetic sector Instrumentation - quadrupole 2 Instrumentation - quadrupole Instrumentation - TOF Instrumentation – ion trap Instrumentation – FT-ICR 3 Instrumentation – FT-ICR Instrumentation – ion mobility Instrumentation – STEP 3: detector – STEP 1: Ion Source – Electron impact Standard 70 eV electron impact ionization http://webbook.nist.gov/chemistry/mw-ser.html 4 – STEP 1: Ion Source – STEP 1: Ion Source - MALDI How to make elephants fly STEP 1: Ion Source - ESI STEP 1: Ion Source - ESI 5 1. Isotopes 3 ways to get more out of a mass spectrum: What does the mass spectrum of C look like? 1. Isotopes (quantitation) 2. Exact mass (resolution + accuracy) 3. Fragmentation (MS/MS) 1. Isotopes 1. Isotopes What does the mass spectrum of C look like? What does the mass spectrum of C look like? What does the mass spectrum of C60 look like? Elemental clues from isotope distributions http://www2.sisweb.com/mstools/isotope.htm http://www2.sisweb.com/mstools/isotope.htm 6 1. Isotopes 1. Isotopes What does the mass spectrum of C look like? Chemical clues from isotope distributions What does the mass spectrum of C60 look like? Water Elemental clues from isotope distributions Chemical clues from isotope distributions Kinetic isotope effect 1. Isotopes 1. Isotopes What does the mass spectrum of C look like? Chemical clues from isotope distributions What does the mass spectrum of C60 look like? Elemental clues from isotope distributions Chemical clues from isotope distributions Isotope mass spectrometry 7 1. Isotopes 2. Mass Accuracy Isotope mass spectrometry Where do mass differences come from? <Einstein> http://webbook.nist.gov/chemistry/mw-ser.html Mass resolution m/Δm 2. Mass Accuracy 3. Fragmentation 1. electron impact 2. CID – collision induced dissociation 3. Electron capture 4. BIRD 5. Successive fragmentation: MS/MS/MS… http://webbook.nist.gov/chemistry/mw-ser.html 8 3. Fragmentation 3. Fragmentation EI Standard 70 eV electron impact ionization http://webbook.nist.gov/chemistry/mw-ser.html 3. Fragmentation 9 10.