Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

What is Mass Spectrometry?

Newton’s second law F = m⋅a

Mass-Energy equivalence

E = m⋅c2 1 eV = ~10-9 amu

F= G⋅m⋅M/r2 r

M

m

Newton Einstein

Gravity

A Mass Spectrometer MagLab - Single Sector Mass Spectrometer Tutorial

MagLab - Dual Sector Mass Spectrometer Tutorial

+

B

-

qv x B

v

qv x B

v

r r

m m

Ion Cyclotron Motion

Marshall and Grosshans, Anal. Chem. 1991, 63, 215A.

m ω = q B

m v2 r = q v B

m v r = q B

ω m q B

= 2πf =

100 ≤ m/z ≤ 3000 corresponds to 35 kHz ≤ f ≤ 1 MHz at 7 tesla

Centripetal Force Magnetic Force

Ion Cyclotron Resonance

kinetic energy distance slit width

Ernest O. Lawrence 1939 Nobel Prize in Physics

Donald Cooksey Cyclotron

Accelerator

T T Magnetic Field (B)

X

Y Z

E

Axial Position

FT-ICR Theory - Ion Trapping

X

Y Z

E

E D

D T

T T E

D

D T

E

T,E T,E D

D E

E D

E

D T

T T T

E,D,T

B

FT-ICR Trap Geometry

B0

Detection

+ + + +

+ + + +

+

R C

Excitation

+ +

+ + + + + +

+

Marshall et. al., Mass Spectrom. Rev. 1998, 17, 1.

fast (~1 ms) scan all m/z simultaneously

Differential Amplifier

FT

100 150 200 250 Frequency (kHz)

7+

8+

10+

11+ 12+

9+

600 1000 1400 1800

12+ 11+

10+ 9+

8+

7+

m/z

0

80 240 400 Time (ms)

Image Charge

Bovine Ubiquitin

1072 1071

m q

B f = _ E

f 2

FT-ICR Tutorial

Frequency (Hz)

Δf50% ~2

observation period (s)

Δm Δf f m = Resolving Power (RP) =

At 7 Tesla, RP is greater than 100,000 at m/z 500 for a 1 s observation

Magnitude-mode lineshape and Hanning apodization

(m/z)max (m/z)min m/z

Peak Capacity = Δm50%

(m/z)max - (m/z)min

Δm50% • • •

Advantages of High Magnetic Field

Mass Resolving Power Acquisition Speed

Mass Accuracy Dynamic Range Kinetic Energy* 21 T

14.5 T

12 T 9.4 T

7 T

Marshall and Guan, Rapid Commun. Mass Spectrom. 1996, 10, 1819-1823

7 T 9.4 T 12 T

14.5 T

21 T

0 0 25 25 B (tesla) B (tesla)

Peak Coalescence

m/z 563.75 563.65 563.55 563.45 563.35 563.25

Low Resolving Power

High Resolving Power

m Δm

= 2500

m Δm

= 350,000

Monoisotopic Mass

m(e-) = 0.000548 Da

0.000452 ± 0.000005 Da

= 3,300,000 Δm m

(S2H8 vs. N4O) RVMRGMR vs. RSHRGHR (MW ≈ 904 Da)

m (Da) 906.496 906.499 906.502

Smallest resolved mass difference between two molecules!

Middle East Crude Oil, (+) APPI at 14.5 T

400 600 800 1000 1200 1400 m/z

505.276 505.298

1000.04

3.4 mDa, C3 vs. SH4

4.5 mDa, 13C vs. CH

3.4 mDa

1000.05

1.1 mDa 3.6 mDa

2.3 mDa 3.6 mDa, C1N1 vs. 13C2

2.3 mDa, C7 vs. S2H713C1

1.1 mDa, SH313C1 vs. C4 49,797 peaks >6σ

m/Δm50% = 800,000 (m/z 400)

500

Molecular mass

105,817 peaks

750 1000 1250 1500 1750 2000

Petroleum = Immense Complexity

m ω = q B

m v2 r = q v B

m v r = q B

ω m q B

= 2πf =

100 ≤ m/z ≤ 3000 corresponds to 35 kHz ≤ f ≤ 1 MHz at 7 tesla

Centripetal Force Magnetic Force

Ion Cyclotron Resonance

kinetic energy distance slit width

X

Y Z

E

E D

D T

T T E

D

D T

E

T,E T,E D

D E

E D

E

D T

T T T

E,D,T

B

E Field Contribution

m v2 r = qvB – qEr

Ledford et. al., Anal. Chem. 1984, 56, 2744-2748.

m ω2r = qBωr – qEr m ω2 = qBω – qE

m q = B

ω E ω2 –

FT-ICR Mass Calibration: E & B Centripetal Force Magnetic Force Electric Force

0 100000 200000 300000 400000 0

1

3

5

7

2

4

6

Frequency (Hz)

m f 2

q (T

h H

z2 x

1013

) FT-ICR Mass Calibration

rms error = 251 ppb m/q = 300-800 n = 34

mω2 q

= Bω E –

0

200

400

600

800

1000

1200

1400

0 100 200 300 400 500 600 Time (hours)

Mag

netic

Fie

ld D

rift (

ppb)

Superconducting Magnet (B field) Stability

2 ppb/hour

0

20

40

60

80

0 2 4 6 8 10 Trap Potential (V)

Freq

uenc

y Sh

ift (H

z)

~8 Hz/V

7 T, m/z 500 30 ppm shift in E leads to 1 ppb mass shift!

Electric Field Stability

What is Molecular Mass? Mass: M = Σme⋅ne, me – mass of an element ne – number of atoms of this element in the molecule

Isotope Mass Abundance Chemical mass 1H 1.00782510 99.9852% 1.00794 2H (D) 2.01410222 0.0148% 12C 12.0(0) 98.892% 12.011 13C 13.0033544 1.108% 14N 14.00307439 99.635% 14.00674 15N 15.0001077 0.365% 16O 15.99491502 99.759% 15.9994 17O 16.9991329 0.037% 18O 17.99916002 0.204% 31P 30.9737647 100% 30.9737647 32S 31.9720737 95.0% 32.066 33S 32.9714619 0.76% 34S 33.9678646 4.22% 36S 35.967090 0.014%

5 lb

2 lb

1 lb

Want a 5 lb weight on the platform:

Want a 10 lb weight on the platform: # of possibilities depends on what?

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

H He

Li

and so on…

Now:

But now everything doesn’t have a integer mass:

5 lb

2 lb

1 lb H = 1.0078 He = 4.0026

Li = 6.9410

So we have a “mass defect” imparted by every atom except carbon 12, since it is the base of the scale at 12.0000

For example: Methane One 12C and four H’s = 12.0000 + (4) x 1.0078 = 16.0312 not 16.0000, have a 0.0312 mass defect

This is why you can assign elemental compositions!

-0.04 -0.03 -0.02 -0.01

0 0.01 0.02

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34

1H

2H 13C 14N 15N

16O

31P 32S 34S

12C

Atomic Mass Defects

(Dalton)

Low resolution

High resolution

1 m/z

m/z 563.75 563.65 563.55 563.45 563.35 563.25

Low Resolution MS

High Resolution MS

m Δm

= 2500

m Δm

= 350,000

This is the way nature works!

0

2

4

6

8

10

521.0 521.1 521.2 521.3 521.4 521.5

(1 mDa Bins) CcHhNnSsOo Mass Space

Mass

How accurate do you have to measure the mass?

0

2

4

6

8

10

521.10 521.105 521.110 521.115 521.120

(1 mDa Bins)

CcHhNnSsOo Mass Space

Mass

0 1 2 3 4 5 6 7

521.100 521.105 521.110 521.115 521.120

(0.5 mDa Bins)

CcHhNnSsOo Mass Space

Mass

0

1

2

3

4

521.110 521.112 521.114 521.116 521.118 521.120

(0.1 mDa Bins)

CcHhNnSsOo Mass Space

Mass

~1 possibility per bin!

700.70 700.65 700.60 700.55 700.50 700.45 700.40

93.9 mDa

m/z 1,000 900 800 700 600 500 400 300

(+) ESI FT-ICR MS European Crude Oil

36.4 mDa

8.2 mDa 3.4 mDa

17.1 mDa

C3 / SH4

N / 13CH

C / H12

O / CH4

13C2 / C2H2

N13C / C2H3

8.9 mDa

Compositional Analysis of Heavy Conventional Crude Oil by FT-ICR Mass Spectrometry

1. Carbon Number 2. Heteroatom Composition 3. Aromaticity

m/z 704.53510

[C50H72S1 + H]+

m/z

m/Δm50%

100 - 400 ppb

DBE = C – H 2

N 2

+ + 1

McLafferty & Turecek Int. Mass Spectra, 1993

[Z = -2(DBE) + n + 2] Carbon Number

S1 Class

Relative Abundance (% total)

DB

E

40

30

20

10

0 20 40 60 80

800 700 600 500 400

*

Advanced Data Processing enables high throughput analysis…

Petro-Org Software Platform

Petroleum: The Structural Controversy

2 Proposed Structural Motifs

Archipelago Island

Energy & Fuels, 14 (1), 2000, 6-10

N+

N CH3

H

Loss of DBE with Carbon

0 60 40 80

40

20

20

10

0

30

DB

E

Carbon Number

Distinction Between Structures

I

A

m/z 1600 1400 1200 1000 800 600 400 200

Petroleum: The Structural Continuum

DAO 4 Ring Fraction (+) APPI FT-ICR MS at 9.4 Tesla SWIFT Isolation at m/z 632

m/z 1600 1400 1200 1000 800 600 400 200

632.6 632.5 632.4 632.3 632.2

S1 S2

HC

HC

S2

S3

S1

S2

S3

S1

DAO 4 Ring Fraction – Single Nominal Mass Isolation

Quad Iso + SWIFT for m/z 632

IRMPD 100 ms IRMPD 500 ms

HC Class HC Class

S1 Class S1 Class

20 40 60 80 00

40

30

20

10

Dou

ble

Bon

d Eq

uiva

lent

s

Carbon Number

40

30

20

10

0

0

40

30

20

10

40

30

20

10

0

20 40 60 80 0

15 25 35 45 5

DBE 10

DBE 17

DBE 23

DBE 26

DBE 14

DBE 20

DBE 7

Carbon Number

Thank You!

Ryan P. Rodgers Ion Cyclotron Resonance Program

rodgers@magnet.fsu.edu