Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Transcription

1 Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

2 What is Mass Spectrometry? Gravity F= G m M/r 2 r M m Newton Newton s second law F = m a Mass-Energy equivalence E = m c 2 1 ev = ~10-9 amu Einstein

3 A Mass Spectrometer MagLab - Single Sector Mass Spectrometer Tutorial MagLab - Dual Sector Mass Spectrometer Tutorial

4 Ion Cyclotron Motion B v m m v + - qv x B qv x B r r Marshall and Grosshans, Anal. Chem. 1991, 63, 215A.

5 Centripetal Force m v 2 r = q v B Magnetic Force m v r = q B m ω = q B kinetic energy distance slit width ω = 2πf = Ion Cyclotron Resonance q B m 100 m/z 3000 corresponds to 35 khz f 1 MHz at 7 tesla

6 Ernest O. Lawrence 1939 Nobel Prize in Physics Donald Cooksey Cyclotron Accelerator

7 FT-ICR Theory - Ion Trapping X Z T T Magnetic Field (B) Y E Axial Position

8 FT-ICR Trap Geometry B Z Y E D T D T E T X T D E E D D D T,E T,E T E D T T E D E T E,D,T

9 Excitation fast (~1 ms) scan Detection all m/z simultaneously B 0 R C Marshall et. al., Mass Spectrom. Rev. 1998, 17, 1.

10 Differential Amplifier Image Charge 0 Bovine Ubiquitin FT-ICR Tutorial FT Time (ms) m q = B f _ E f Frequency (khz) m/z

11 Resolving Power (RP) = f Δf m = Δm Magnitude-mode lineshape and Hanning apodization ~2 observation period (s) At 7 Tesla, RP is greater than 100,000 at m/z 500 for a 1 s observation Δf 50% Frequency (Hz)

12 Peak Capacity = (m/z) max - (m/z) min Δm 50% Δm 50% (m/z) min m/z (m/z) max

13 Advantages of High Magnetic Field Mass Resolving Power Acquisition Speed 14.5 T 21 T Mass Accuracy Dynamic Range Kinetic Energy* Peak Coalescence 21 T 9.4 T 7 T 12 T 7 T 12 T 9.4 T 14.5 T 0 B (tesla) 25 0 B (tesla) 25 Marshall and Guan, Rapid Commun. Mass Spectrom. 1996, 10,

14 Low Resolving Power High Resolving Power m Δm = 2500 m Δm = 350, m/z

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16 RVMRGMR vs. RSHRGHR (MW 904 Da) Monoisotopic Mass (S 2 H 8 vs. N 4 O) ± Da m Δm = 3,300,000 m(e - ) = Da m (Da) Smallest resolved mass difference between two molecules!

17 m/z Middle East Crude Oil, (+) APPI at 14.5 T 3.6 mda 1.1 mda 2.3 mda 3.6 mda, C 1 N 1 vs. 13 C mda, C 7 vs. S 2 H 7 13 C mda, SH 3 13 C 1 vs. C 4 49,797 peaks >6σ m/δm 50% = 800,000 (m/z 400) 3.4 mda, C 3 vs. SH mda, 13 C vs. CH 3.4 mda

18 Petroleum = Immense Complexity 105,817 peaks Molecular mass

19 Centripetal Force m v 2 r = q v B Magnetic Force m v r = q B m ω = q B kinetic energy distance slit width ω = 2πf = Ion Cyclotron Resonance q B m 100 m/z 3000 corresponds to 35 khz f 1 MHz at 7 tesla

20 E Field Contribution B Z Y E D T D T E T X T D E E D D D T,E T,E T E D T T E D E T E,D,T

21 FT-ICR Mass Calibration: E & B Centripetal Force Magnetic Force Electric Force m v 2 r = qvb qer m ω 2 r = qbωr qer m ω 2 = qbω qe m q = B ω E ω 2 Ledford et. al., Anal. Chem. 1984, 56,

22 FT-ICR Mass Calibration 7 (Th Hz 2 x ) mω 2 q = Bω E m f 2 q 2 1 rms error = 251 ppb m/q = n = Frequency (Hz)

23 1400 Superconducting Magnet (B field) Stability Magnetic Field Drift (ppb) ppb/hour Time (hours)

24 Frequency Shift (Hz) Electric Field Stability 30 ppm shift in E leads to 1 ppb mass shift! 7 T, m/z 500 ~8 Hz/V Trap Potential (V)

25 What is Molecular Mass? Mass: M = Σm e n e, m e mass of an element n e number of atoms of this element in the molecule Isotope Mass Abundance Chemical mass 1 H % H (D) % 12 C 12.0(0) % C % 14 N % N % 16 O % O % 18 O % 31 P % S % S % 34 S % 36 S %

26 Want a 5 lb weight on the platform: 1 lb 2 lb 5 lb Want a 10 lb weight on the platform: # of possibilities depends on what?

27 Now increase the # of blocks to the # of elements and their masses to atomic mass units. The number of possibilities drastically increases as the mass of the molecule (or weight on the scale ) increases and as the number of weights (or atoms) increases Now: H He Li and so on

28 But now everything doesn t have a integer mass: 1 lb H = lb 5 lb He = Li = So we have a mass defect imparted by every atom except carbon 12, since it is the base of the scale at For example: Methane One 12 C and four H s = (4) x = not , have a mass defect This is why you can assign elemental compositions!

29 (Dalton) 0.02 Atomic H 2 H 13 C 14N 15N Mass Defects C 16 O P 32 S 34S

30 Low resolution High resolution 1 m/z

31 This is the way nature works! Low Resolution MS High Resolution MS m Δm = 2500 m Δm = 350, m/z

32 How accurate do you have to measure the mass? 10 C c H h N n S s O o Mass Space (1 mda Bins) Mass

33 C c H h N n S s O o Mass Space 10 (1 mda Bins) Mass

34 C c H h N n S s O o Mass Space 7 (0.5 mda Bins) Mass

35 ~1 possibility per bin! C c H h N n S s O o Mass Space 4 (0.1 mda Bins) Mass

36 C / H mda 13 C 2 / C 2 H mda European Crude Oil (+) ESI FT-ICR MS N 13 C / C 2 H mda O / CH mda C 3 / SH mda N / 13 CH 8.2 mda m/z ,000

37 Compositional Analysis of Heavy Conventional Crude Oil by FT-ICR Mass Spectrometry * m/z m/δm 50% 1. Carbon Number 2. Heteroatom Composition 3. Aromaticity H N DBE = C McLafferty & Turecek Int. Mass Spectra, 1993 [Z = -2(DBE) + n + 2] m/z [C 50 H 72 S 1 + H] + DBE Relative Abundance (% total) ppb S 1 Class Carbon Number

38 Advanced Data Processing enables high throughput analysis Petro-Org Software Platform

39 Petroleum: The Structural Controversy 2 Proposed Structural Motifs Island Archipelago N CH 3 N + H Loss of DBE with Carbon Energy & Fuels, 14 (1), 2000, 6-10

40 40 Distinction Between Structures 30 DBE 20 I 10 0 A Carbon Number

41 Petroleum: The Structural Continuum m/z

42 DAO 4 Ring Fraction (+) APPI FT-ICR MS at 9.4 Tesla SWIFT Isolation at m/z m/z

43 DAO 4 Ring Fraction Single Nominal Mass Isolation Quad Iso + SWIFT for m/z 632 S 1 S 2 HC S 3 S 1 S 2 S 3 S 2 HC S 1

44 40 IRMPD 100 ms HC Class 40 IRMPD 500 ms HC Class Double Bond Equivalents S 1 Class S 1 Class Carbon Number

45 DBE 26 DBE 23 DBE 20 DBE 17 DBE 14 DBE 10 DBE Carbon Number

46 Thank You! Ryan P. Rodgers Ion Cyclotron Resonance Program