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Advanced Mass Spectrometry. F LORIDA I NTERNATIONAL U NIVERSITY . Piero R. Gardinali /Yong Cai/ Bruce McCord. Revised on August 23, 2009. First Steps. Introduction to mass spectrometry Definition of common terms A generic mass spectrometer Formation of ions The mass spectrum
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Advanced Mass Spectrometry
FLORIDA INTERNATIONAL UNIVERSITY
Piero R. Gardinali/Yong Cai/ Bruce McCord
Revised on August 23, 2009
Mass spectrometry is a powerful analytical technique that is used to identify unknown compounds, to quantify known materials, and to determine the structural and chemical properties of molecules.
Detection of compounds can be accomplished with very minute quantities. (as little as 10 -12 grams).
1968
1988
Fenn developed ESI in 1988; Concept was proposed by Dole in 1968. Fenn received Nobel Prize in 2002
1918
Anode rays
Goldstein
1886
Electron m/z
Thomson
1897(Nobel Prize in 1906)
Magnetic deflection
Positive Ions
Wein
1898
Unit of charge
Millikan & Fletcher
1909
First parabola
Spectrograph
Thomson
1912
Metastable ions
Thomson
1913
1966
1953
1969
1952
1946
1980
1940
Nier
U-235
1956
Exact Mass
Benyon
1974
1978
1981
1987
1956
1919
Develop first MS with velocity focusing, Nobel Prize in 1922
Still spectroscopy?
What is a mass spectrometer?
Illustration of the basic components of a mass spectrometry system.
Ionization
Source
Mass
Analzyer
Detector
selected
ions
Data
System
Inlet
all ions
The mass spectrum
%Relative Abundance
1265.0000321
843.00
421.0
360
m/z
What do I get from the instrument?
Mass spectrum of methanol by EI,
presented as a graph and a table
The most intense peak of a mass spectrum is called base peak
Often used in stoichiometric calculations.
Use monoisotopic mass if possible in MS
C20H42C100H202
Nominal: (20 x 12) + (42 x1) = 282 u(100x12) + (202x1) = 1402u
Monoisotopic: (20 x12) + (42 x 1.007825) = 282.33(100x12) + (202x1.007825) = 1403.5807
Average: (20 x 12.011) + (42 x 1.00794) = 282.5535(100x12.011)+(202x1.00794) = 1404.7039
HOW DO I CREATE AN ION?
M + e- M.+ + 2e-
HOW DO I CREATE AN ION?
M + e- M.+ + 2e-
HOW DO I CREATE AN ION?
M + e- M.+ + 2e-
An then what?
Radical cation
HOW DO I CREATE AN ION?
M + e- M.+ + 2e-
K: Boltzmann constant,
T: temperature (in K)
p: pressure (in Pa)
: collision cross-section (in m2)
P in pascals
P in milli Torrs