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CU-Boulder CHEM 5181 - Mass Analyzers III

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2Mass Analyzers IIISector, FTICR, OrbitrapCU- Boulder CHEM 5181: Mass Spectrometry & ChromatographyProf. Jose-Luis JimenezFall 2007High VacuumSample InletIon SourceMassAnalyzerDetector RecorderMS Interpretation Lectures3MS Oscilloscopehttp://www.vias.org/simulations/simusoft_msscope.html4An Ion in an Uniform Magnetic Field• Q: what determines the radius of rotation?From Watson5Simulation of Magnetic Sector MS• Clicker Q• With Vs= 4000 V and B = 200 mT, we select m/z 35.•What m/z will we select if we double both Vsand B?A. m/z 35B. m/z 17.5C. m/z 70D. m/z 350E. All of the abovehttp://www.vias.org/simulations/simusoft_ms_sectorfield.html6Magnetic Sector Analyzer• Ion kinetic energy when leaving source:• Action of the magnetic field:• Trajectory of ion is determined by equilibration of magnetic force and centripetal acceleration:• Ions with the same momentum (mv) have the same R. This is a momentum analyzer.• Taking into account the kinetic energy of the ions:skqVmvE ==22BxvqFMrrr =RmRmvqvB22ω==qBmvR =sVBRqm222=7Simulation of Magnetic Sector MS• Clicker Q• With Vs= 4000 V and B = 200 mT, we select m/z 35.•What m/z will we select if we double Vsand halve B?A. m/z 4B. m/z 17.5C. m/z 35D. m/z 70E. m/z 140http://www.vias.org/simulations/simusoft_ms_sectorfield.html8Magnetic Sector Analyzer Part II• Fixed geometry instruments– If R is fixed by the geometry of the analyzer, for a given B only one m/z will reach the detector– Can be scanned by scanning B or Vs• Dispersive instruments– measure ions arriving with different R• Problem: ions with the same mEk/q have same R:• Use electrostatic analyzer to narrow EkrangeqmEBRk21=9Clicker Question• An ion source produces ions of with an average energy of 5000 V and an energy dispersion of 100 eV. Can we use a magnetic-only analyzer with this source to separate ions at m/z 200 with a resolution of 10000?A. YesB. MarginallyC. NoD. I don’t know10Magnetic Sector AnalyzerFrom Watson• Popular for certain applications, e.g. Prof. Jim White (ENVS) has 7 of these in East Campus for isotope ratio MS11Electric Sector AnalyzerFrom Barker++ + +_ _ _12Electrostatic Analyzer• Ion kinetic energy when leaving source:• Action of the electric field:• Trajectory of ion is determined by equilibration of electric force and centripetal acceleration:• Ions with the same kinetic energy have the same R:• So trajectory is independent of the mass, and this is really a kinetic energy analyzerskqVmvE ==22EqFErr =RmRmvqE22ω==qEERk2=13Double Focusing Mass AnalyzerFrom Barker• Electric analyzer passes a narrow range of Ek• So that magnetic analysis is really of m/q14ICR Geometry, Excitation, & Ion MotionFrom Hoffmann15FTMS: Time to Frequency ConversionFrom Lambert• No traditional detector (multiplier, MCP)16FTMS Extreme ResolutionFrom Watson17FT-ICR MS: Sensitivity & non-destructivenessFrom Hoffmann18OrbitrapCutaway view of the Orbitrap mass analyzer.Ions are injected into the Orbitrap at the point indicated by the red arrow. The ions are injected with a velocity perpendicular to the long axis of the Orbitrap (the z-axis). Injection at a point displaced from z = 0 gives the ions potential energy in the z-direction. Ion injection at this point on the z-potential is analogous to pulling back a pendulum bob and then releasing it to oscillate. Perspective: The Orbitrap: a new mass spectrometer. Q. Hu, R.J. Noll, H. Li, A. Makarov, M. Hardman, R. Graham Cooks. J. Mass Spec., 40(4): 430 – 443, 2005.http://www.chem.purdue.edu/iii/Orbitrap%20Instrument.htmkmq=ωFFTTransientMass Spectrumm/zm/z19Orbitrap II• C-Trap for injection• Linear ion trap interface• Orbitraps have a high mass accuracy (1-2 ppm), a high resolving power (up to 200,000) and a high dynamic range (around 5000)http://www.thermo.com/com/cda/resources/resources_detail/1,,200176,00.html20Example Orbitrap Datam/z1,8001,6001,4001,200+5+4+31,1491,1481,147+5m/Δm = 70,0001,1491,1481,147+5m/Δm = 70,0001,4361,4351,434+4m/Δm = 45,0001,4361,4351,434+4m/Δm = 45,0001,9141,9131,9121,911+3m/Δm = 40,0001,9141,9131,9121,911+3m/Δm = 40,000Instrument performance for Bovine InsulinInstrument performance for Bovine Insulinhttp://www.chem.purdue.edu/iii/Orbitrap%20Instrument.htm21Clicker Question: High-Resolution MS• The use of ultrahigh resolution MS:A. Eliminates the need for chromatographic separationB. Reduces the need for chromatographic separationC. Does not reduce the need for chromatographyD. I don’t knowE. All of the above22As Impressive as this is, often it is not enough on its own!Metabolomic database annotations via query of elemental compositions: Mass accuracy is insufficient even at less than 1 ppm. Tobias Kind and Oliver Fiehn. BMC Bioinformatics 2006, 7:234, doi:10.1186/1471-2105-7-234. http://www.biomedcentral.com/1471-2105/7/234 Figure 4: Trend pattern histogram for mathematical possible number of molecular formulae (C, H, N, S, O and P) for the mass range 200 u-300 u. A step size of 0.01 u was taken for counting the number of formulae. 23Hybrid InstrumentsFrom Hoffmann• Very common,combine the advantages of various analyzers24Progress of MS AnalysisFrom James (Ed.). “Proteome Research:Mass Spectrometry.”Springer, 2000. (QP551 .P7558 2001 at CU Libraries)25Comparison of Mass Analyzers IFrom Lambert26Comparison of Mass Analyzers IIG. Siuzdak. “Mass Spectrometry for Biotechnology.” Academic Press, 1996. QP519.9.M3 S58 1996 at CU Libraries.27Comparison of Mass Analyzers IIIC. Dass. “Principles and Practice of Biological Mass Spectrometry.” Wiley Interscience, New York, 2001. QP519.9.M3 D33 2001 at CU


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