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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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 used to identify unknown compounds, to quantify known materials, and to determine the structural and chemical properties of molecules.
Fenn developed ESI in 1988; Concept was proposed by Dole in 1968. Fenn received Nobel Prize in 2002
1897(Nobel Prize in 1906)
Unit of charge
Millikan & Fletcher
Develop first MS with velocity focusing, Nobel Prize in 1922
Still spectroscopy? Solution, Sensitivity, Mass Range, and Accuracy
What is a mass spectrometer? Solution, Sensitivity, Mass Range, and Accuracy
Illustration of the basic components of a mass spectrometry system.
The mass spectrum Solution, Sensitivity, Mass Range, and Accuracy
What do I get from the instrument? Solution, Sensitivity, Mass Range, and Accuracy
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
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? or ion
M + e- M.+ + 2e-
An then what?
Radical cation or ion
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