A 318 Lecture 2324 Ms Analyzers Hand Out

7/27/2019 A 318 Lecture 2324 Ms Analyzers Hand Out

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Sample Exam Questions1. _____ Ions formed by ___ obtain multiple charges via proton transfer.

A. EI

B. FAB

C. ESI

D. MALDI

2. _____ Which source should be use to produce singly charged parent ionsfor myoglobin (16591 Da)?

A. CI

B. EI

C. ESI

D. MALDI

Mass AnalyzersContinuous (Filters)Quadrupole - Quad

Magnetic Sector - MS

Electrostatic Analyzer - ESA

Pulsed

Time-of-Flight (Reflectron) - TOF

Ion Trap (quadrupole or linear) IT (QIT or LIT)

Fourier Transform Ion Cyclotron Resonance FTICR

Orbitrap

Tandem

Triple-Quad, Ion trap, FTICR, Q-TOF, TOF-TOF, IT-FTICR, IT-Orbitrap


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Mass Resolution / Mass Range

Instrument

11C,20C

Resolution ability of mass analyzer to separate ions w/ similar m/z values

Peaks are considered resolved if height of valley between them is less than10% of peak height

Resolution, R = m/m R = 27.5/1 = 27.5 to resolveAl+ from Si+

Al+ Si+

27 28

R = ~50

Al+ Si+

27 28

R = ~100

Al+ Si+

27 28

R = ~500

Nominal mass nearest whole number mass (28 for CO, 44 for CO2

)

Mass Range from smallest to largest m/z separated by mass analyzer

Quadrupole Mass Analyzer

Instrument

11B

Most commonly used bench-top mass analyzer inexpensive, rugged,compact, high scan rates (100 ms/spectrum)

+

+- -

four parallel cylindrical rods

opposite rodshave samepotential

stabletrajectory

unstable trajectory

One set of rods acts as low-pass filter, the other as high-pass filter

m/z

T

m/z

T

m/z

Tcombined

(Figures 11-4, 11-5, 11-6, 11-7)


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Various Ion Guides Multi-poles

Figure 5. Radial pseudopotential contour in volts forthe multipoles and tripole cross-section. All graphsshow that the minimum point is in the center of eachmultipole and increases when it moves to the

electrodes. Calculation conditions: V0 = 10 V, = 1MHz, r0 = 3 mm, 1000 Da, ion charge = +1. (a)

quadrupole; (b) hexapole; (c) octapole; (d) tripole.

Figure 6. Ion guides AC voltage for stable ionguiding and tripole stable trajectory. 1 MHz,length 150 mm, r0 = 3 mm. Beam initialconditions: kinetic energy 10 eV, expansion

angle 3, and initial radius = 0.5 r0. (a) AC-mass stability diagrams; (b) cross-section view;(c) transversal view of the ion stable movementinside of the tripole rotational electric field.

Computer Simulations of a New Three Rods Ion Optic (TRIPOLE) with High Focusing and Mass Filtering Capabilities GaryAbdiel Salazar, Tsutomu Masujima J. American Society for Mass Spectrometry Vol. 18, Iss. 3 , March 2007, 413-421.

Einzel Lens Ion beam focusing

This shows the path of ions as they travel through a simulated Einzel lens. The ion mass is 200kDaaccelerated to 40kV, the middle plate potential is at 200V and the plate size is 1m these are verylarge settings used to show the focusing effect more easily and are not practical settings.

plates

OR

rings

Divergent ion beams arecollimated / focused afterpassing through 3-voltageelement

http://en.wikipedia.org/wiki/Einzel_lens

plates+V volts0 volts

0 volts 0 volts

0 volts

+V volts

ion path focus

Electric field lines


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Magnetic Sector / Electrostatic Analyzer

Instrument

11B, 20C

Double-focusing mass spectrometer

Corrects for energy (in ESA) and directional (in MS) distributions of ions capable of very high (105) resolution - Single-focusing (MS only)instruments have lower (~2000) resolution

In MS: m/z = B2r2e/2V, scan by varying B, V, or r

Several arrangements for double-focusing instruments 2 common onesare Mattauch-Herzog (Fig. 11-9) with plane of double-focus & Nier-Johnson (Fig. 20-13) with point of double-focus

ESA

MS

focalplane

m1/zm2/z

3150

Mattauch-Herzog Nier-Johnson

point ofdoublefocus

MS

energy

focal planedirection

focal plane

ESA

ESA slit

+

+

-

-

Time-of-Flight Mass Analyzer

zm

eV

dt2

=

Instrument

11B, 20C

Brief pulses (few ns) of ions produced at 10 Hz to 50 kHz and acceleratedby 1 to 20 kV into ~1-m field-free drift region where ions separate asinverse of m/z lighter ions arrive at detector prior to heavier ions flighttimes of 1 to 30 s requires very fast (ns bins) electronics

0 V10 kV

large

electricfield

signal

detector1 m

field-free region

Simple, rugged, simultaneous detection, virtually unlimited mass range,rapid data acquisition (


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Delayed Extraction TOF MS

Instrument

notes

Ions formed in source under field-free conditions (usually desorption from

surface), allowed to drift due to inherent velocity after brief delay, electricfield is applied, pushing ions toward detector such that ions w/ smallerinitial velocities receive more acceleration, reaching detector at same timeas ions of same m/z with larger initial velocities

initial desorption(0 s)

5 kV

5 kV

0 kV

delayed extraction(0.1 to 5 s)

0 kV

5 kV

10 kV

Length of delay and size of pulse determine the m/z that isoptimally focused

Reflectron Time-of-FlightMass Analyzer

amp comp

0 kV

L+M+H+

+20 kV

+22 kV

0 kV 0 kV

0 kV

1) Ions enter source region,accelerated toward reflectron.

2) Ions separate in space based ontheir relative mass-to-charge (m/z).

3) Ions reverse path in reflectron.

4) Ions impact detector.

Flight time

Signal

Instrument

notes


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Ion Trap Mass Analyzer

Instrument

20C

Quadrupole (3-D) ion trap consists of a donut-shaped ring electrode & two

end cap electrodes (Fig. 20-15) ions enter through one end cap, arestabilized by radio-frequency voltage applied to ring electrode while endcaps are at ground ions of individual m/z are sent through other end capto detector during scan rugged, compact, inexpensive

todetector

fromsource

endcaps

ringelectrode

Linear (2-D) ion trap resembles quadrupole mass analyzer

3D ion trap

http://aemc.jpl.nasa.gov/activities/mms.cfm


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2D (linear) Ion Trap MS

Simion simulation of the resonanceexcitation field comparing (a) a threesection device and (b) a single section

device with end plates for axial trapping.

(a) Simion simulation of 100 eV ions

exiting the 2-D trap along the length ofthe exit slot and being focussed ontothe 15kV conversion dynode. (b) 10keV ions simulated.

A two-dimensional quadrupole ion trap massspectrometer Jae C. Schwartz, Michael W. Senko,and John E. P. Syka J. American Society for Mass

Spectrometry Vol. 13, Iss. 6 , June 2002, 659-669.

Linear Ion Trap Instrument

The overall instrument configuration along with typical operating voltages and pressures.

A two-dimensional quadrupole ion trap mass spectrometer Jae C. Schwartz, Michael W. Senko, and

John E. P. Syka J. American Society for Mass Spectrometry Vol. 13, Iss. 6 , June 2002, 659-669.

ion transmissionmass

analysis


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FT Ion Cyclotron Resonance

Instrument

20C

Ions trapped in cubic cell inside bore of (usually superconducting) magnet

excited from center by brief RF pulse into circular path in planeperpendicular to magnetic field, B (Fig. 20-16, 20-17)

transmitterplate

receiverplate

receiverplate

B

Electronsdrawn throughcircuit as ionsapproach /recede fromreceiver plates

Image current measured through circuit depends on the Free-InductionDecay (FID) of ions in their characteristic cyclotron frequency,c

zeB

mc=

FTICR Signal Processing

Instrument

20C

Excitation RF

FID signal

time

Frequency (kHz)

zeB

mc=

m/z (amu)

FT

Capable of very high (>106) resolution,improves with longer FID signal; veryexpensive (>$400k) due tosuperconducting magnet (>3 T)


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Orbitrap MS

http://www.thermo.com/eThermo/CMA/PDFs/Various/File_31081.pdf

http://www.thermo.com/eThermo/CMA/PDFs

/Articles/articlesFile_30850.pdf

High Resolving Power example

http://www.thermo.com/eThermo/CMA/PDFs/Articles/articlesFile_30850.pdf

Phosphatidylethanolamines

PE 18:0/18:0 and

PE O-16:1p/22:6

(isobaric)

Larger resolvingpower requires moretime per scan.


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Mass Analyzer Figures of Merit

Instrument

20C

Resolution m/z range scan time

Quadrupole Quad ~2000 < 2000 100 ms

Magnetic Sector ~2500 < 2000 ~1 s

Double-focusing (ESA/MS) 50,000 < 2000 ~1 s

Time-of-Flight ~4000 unlimited 100 s

Reflectron TOF 20,000 unlimited 100 s

Ion Trap (3D) ~2000 < 2000 100 ms

Linear (2D) Ion Trap ~2000 < 2000 20 ms

FTICR > 200,000 50,000+ 0.1-10 s

Orbitrap > 50,000 50,000+ 0.1-10 s

Tandem Mass Analyzers

Instrument

notes

Perform tandem mass spectrometry single m/z is isolated, fragmented,and daughter ions are scanned

Triple-Quad collision-induced dissociation (CID) in 2nd quad

Ion trap isolate parent ion in trap, CID, scan daughter ions

FTICR excite unwanted ions from trap, collide ions w/ surface, recordFID of fragments

Q-TOF select precursor in quad, CID, send fragments into TOF

TOF-TOF ion gate selects precursor from TOF1, CID or PID to makefragments

IT-FTICR/IT-Orbitrap select precursor in ion trap, fragment, analyzefragments in FTICR/Orbitrap OR mass analyze precursors inFTICR/Orbitrap while isolating/fragmenting/mass analyzing fragments inIT (usually LIT)

A 318 Lecture 2324 Ms Analyzers Hand Out

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