Mass spectrometry, Ion motion in the commonly used mass analyzer.pdf

Mass spectrometry,
Ion motion in the commonly used mass analyzer
This way
Trap
322.6 Da
322.5325153 Da
17825.5 Da
Quadrupole Orbitrap
Ion cyclotron
Time to Flight
Linear trap
Magnetic
A. Prof. Sherif M. Taha
Tel: 01004724944
sherif2taha@gmail.com
‫ميحرلا نمحرلا هللا مسب‬

The commonly used mass to charge analyzer

A quadrupole
Development of the Quadrupole
https://doi.org/10.1016/S1044-0305(02)00385-9

A quadrupole
https://www.sciencedirect.com/topics/earth-and-planetary-
sciences/quadrupole
Using alternative and direct currents (AC and DC)
Quadrupole
Creation of Electric
field between 4 poles
Linear Quadrupole
(controlling Radial (X, Y) ion motion)
3D Quadrupole
(controlling ion motion in 3D)
Design
Linear
3D
https://m-malinowski.github.io/2022/02/21/all-kinds-of-ion-traps.html J.H. Gross, Mass spectrometry Mass spectrometry, 2016
X
X
Y
Y
Controlling Fields
𝑋
𝑌
𝑍

Operation modes of the
Quadrupole
A quadrupole
https://www.sciencedirect.com/topics/earth-and-
planetary-sciences/quadrupole WP-10427-GC-LC-MS-Workhorses-Quadrupoles-Ion-Traps-
WP10427-EN.pdf
 Mass Filter (Specific m/z has stable motion )
 Ion guide/ Ion transmission (just focusing a wide range of m/z)
 Ion fragmentation/ Collision cell)
 Linear Ion trap

A quadrupole as a mass filter
Equation of motion in the Quadrupole field
A periodically varying voltage (ɸ) was applied on the quadrupole electrodes (of same
sign for opposing pairs)
ɸ = 𝑈 + 𝑉ꙍ 𝑡
Serious of math
equations
Paul eq. Mathieu eq.
A positive potential )+( U+V cos Ꙍ t
A negative potential (-) U+V cos Ꙍ t
𝑋
𝑌
𝑍
An Ion having an oscillating motion at r
(between the center of the quadrupole and the
surfaces of the electrodes, X and Y )
a, q & 1/ m/Z
U, V & m/Z
E. Hoffmann, V. Stroobant, Mass spectrometry Mass spectrometry, 2016
X
Y
Z
𝑑 𝑧
𝑑𝑡
= 0

A quadrupole as a mass filter
At specific U and V (specific a and q values, time variable) a specific m/z has a
stable radial motion along X and Y (r < r0).
Stable at Y
Stable at X
Edward
X
X
Y
Y r0
a, q & 1/ m/Z
U, V & m/Z
Equation controlling the ion motion in the Quadrupole field
(Radial motion control)
a or U / q or V

Quadrupole as a mass filter/the scan Line
• Each m/z has its stable region (a/q)
• Increasing U and V (by 2U/V) enables stability (X &Y) of larger masses
𝑋
𝑌
𝑍
U
V
High resolution
Low resolution
Slope= 2U/ V
Controlling radial
ion motion
X
Y
Z
𝑑 𝑧
𝑑𝑡
= 0
J.H. Gross, Mass spectrometry Mass spectrometry, 2016

RF-ONLY quadrupole ( ion guide/Collision cell/Q-trap)
If U= Zero
Specific range of m/z will have stable radial motion (x& y)
If U= Zero
• At V1 m/z ≤ M1 will have stable trajectory
• At V2 M1 < m/z ≤ M2 will have stable trajectory
Ion of stable motion
Radial motion X, Y
(RF only)
Ion guide/Trap (RF-only quadrupoles)
2
0
M 2 3
U
V
V1 V2 V3
Ion guide

O.D.S. J. THROCK WATSON, Introduction to mass spectrometry, (2019)
• A quadrupole as an Ion guide uses RF only to stabilize and focus set of ions
radially (X and Y).
• A quadrupole as a mass filter uses RF and Dc to stabilize a specific ion Radially
(X and Y).
M 2 3
U
V
V1 V2 V3
Ion guide

RF-only hexapoles and octapoles are more preferred as ion guides and also as collision cells ,
since it introduce a better wide-band spread and pass along the center of the quadrupole
https://doi.org/10.1002/mas.20004
RF-ONLY quadrupole ( number of poles)

• Larger molecules containing stronger atomic bonds
require higher Energy to be fragmented.
• The ions fragmented through a cleavage at the weakest
bonds.
• Fragments are produced from by accelerating the
entrance of precursor molecules (different kE, based on
its stability) and its collision with inert gas (low to high
pressure). This gas minimize E difference of ions (remove
excess Energy from ions). Heavier gases (argon, xenon,
krypton) allow the transfer of more energy compared to
Helium and nitrogen gases.
• A gas leads also to collisional focusing towards the
collision cell axis.
Inert gas of low to high E
(perpendicular to the ion beam)
DC Trapping electrode (electrodes of slightly
higher potential than that of quadrupole)

Collison cell: RF-ONLY quadrupole, Hexaploe, Octopole
For ion focusing sending them in bunches into a mass analysers
(Quadrupole, TOF, ..) , and fragmentation.
A bent geometry Increase the removal efficiency of neutrals
(decrease noise)
Collision cell (RF-only
quadrupoles)
2
Buffer gas; N2 / Ar /He
Increase vacuum pressure improve collisional
focusing (this high pressure (collision cell)
compared to lower ones at other quadrupoles (Q1
and 3).
DC Trapping electrode (electrodes
of slightly higher potential than that
of quadrupole)

RF-ONLY quadrupole (ion guide/Collision cell/Q-trap)
Ion trap/ collision
Stages of DC axial ion motion control
At RF only mode ( stable ion motion X, Y)
Ion collection Axial ion ejection
M
v
v A very low v
Negative DC
Voltage
M
v A very low v v
A very low v
M
0 v v
collision associate/ induced collision (CAD/CID)used for further identification (MRM) and some ions
already have shorter lifetime

RF-ONLY quadrupole as ion trap with radial ejection
Ions of different voltage radially ejected
towards the negative dynode
RF only; Stable Radial motion (X and Y)
DC; Stable axial motion (z) RF only (values that induce instability);
Unstable Radial motion (X and Y)

Operation modes of the Quadrupole
A quadrupole
https://www.sciencedirect.com/topics/earth-and-
planetary-sciences/quadrupole
 Mass Filter (Specific m/z has stable motion using AC (RF) and DC).
 Ion guide/ Ion transmission (A stable and focused motion (Radial, X and Y) for a wide range of m/z using AC (RF)
only.
 Collision cell (the precursor ion (selected by a pre mass filter) and produced fragments have a stable motions
(radial) using AC (RF) only, the ion trapping and ejections accomplished using DC (Axial, Z).
 Ion trap (A stable ion motion (Radial) using AC (RF) only, with trapping and ejection using DC (Axial). Radial
ejection can be accomplished by varying the RF.

Explore the ion motion and applied fields
QqQ (MRM)
qqScan
Scanqq
qqQTrap

The orbitrap as a mass to charge analyzer, axial oscillation
central wire
electrode of r
(Cathode)
cylindrical outer
electrode of R
(Anode)
Appling DC
of different
potential, V
Ions have a stable radial (orbital) motion at
𝑉 >
𝑚𝑣2
2𝑞
𝑅
𝑟
Kingdon trap
Ions have a stable axial motion
by end cap electrodes (DC)
ideal Kingdon trap
Knight-style
Collect ions and radial ejection
refined Knight-style Kingdon trap
Orbitrap
logarithmic potential
Quadrupole potential

The orbitrap as a mass to charge analyzer
Axial oscillations
(along z coordinates)
Radial oscillations
(around the central electrode at different radius)
Orbital oscillations
(around the central electrode)
Images of different m/Z currents that induced by its frequency axial motions were
detected by connecting the outer electrodes by a differential amplifier
Ions enter the orbitrap and take the referred shape (elongated along z axis) around the central electrode then it be diminished to be closed as a concise ring of ions
having same m/z , the axial motions (axial oscillations) of these rings (nearly ring shapes) is characteristics to m/z.

The orbitrap as a mass to charge analyzer
https://www.creative-proteomics.com/support/q-exactive-hybrid-quadrupole-orbitrap-mass-spectrometer.htm
q as Ion guide
q as Ion guide
Q mass filter
q Linear ion trap (C)
q collision cell q as Ion guide

Ion cyclotron mass to charge analyzer, cyclotron frequency
Trapping electrode
Ion excitation (AC), increase the radius of
ion magnetron rotation (+/-)
N
S
Centripetal/Lorentz force (F1) 𝐹1 = 𝑧𝑣𝐵
Centrifugal force (F2) 𝐹2 =
𝑚𝑣2
𝑟
Circular/cyclotron frequency (f) 𝑓 =
𝑣
2𝑝𝑖𝑟
=
𝑧𝐵
2𝑝𝑖𝑚
At stable ion trajectory (F1=F2), AC or RF
stopped then Fourier transformer used to
detect m/z by a relation to cyclotron
frequency
FT (detection)
https://analyticalsciencejournals.onlineli
brary.wiley.com/doi/10.1002/mas.21414
Edward
𝑣
2𝑝𝑖𝑟
=
𝑧𝐵
2𝑝𝑖𝑚
https://www.mindfulchildaerialyoga.com/the-
impact-of-spinning-on-your-childs-body-and-mind/

Ion cyclotron () mass to charge analyzer
https://analyticalsciencejournals.onlineli
brary.wiley.com/doi/10.1002/mas.21414
Cyclotron_Mass Spectrometry Reviews - 2014 - Qi - Data processing in Fourier transform ion cyclotron resonance mass spectrometry.pdf

Magnetic mass to charge analyzer, momentum
Edward
Lorentz force/ Magnetic (F1) 𝐹1 = 𝑞𝑣𝐵
Centrifugal/ Centripetal force/ (F2) 𝐹2 =
𝑚𝑣2
𝑟
An ion has stable circular trajectory at F1=F2, 𝑚𝑣 = 𝑞𝐵𝑟
At every B, a specific ion (same momentum [mv]or specific mass and same kinetic energy or same velocity and charge
has specific radius trajectory (r).
𝐾𝑖𝑛𝑒𝑡𝑖𝑐𝑘 𝐸𝑛𝑒𝑟𝑔𝑦 =
1
2
𝑚𝑣2
Electric potential Energy, a potential V = ezV
𝑚𝑣2
=2 qV
𝑣 2
=
2𝑞𝑉
𝑚
𝑚
𝑞
=
𝐵𝑟
𝑣
𝑚=
𝐵2𝑟2𝑞
2𝑉
𝑚
𝑞
=
𝐵2𝑟2
2𝑉
𝑚
𝑒
=
𝑧𝐵2𝑟2
2𝑉
𝑚2
𝑞2 =
𝐵2𝑟2
𝑣2 =
𝐵2𝑟2𝑚
2𝑞𝑉
kinetic energy
the kinetic energy of the ions can be controlled using electrostatic analyzers

Magnetic mass to charge analyzer, momentum
ions of different KE entering B follow different trajectories
𝐸𝑛𝑒𝑟𝑔𝑦 𝑑𝑖𝑠𝑝𝑒𝑟𝑠𝑖𝑜𝑛 𝐸𝑛𝑒𝑟𝑔𝑦 𝑑𝑖𝑠𝑝𝑒𝑟𝑠𝑖𝑜𝑛
Energy Focusing

Time-of-flight (TOF) mass to charge analyzer, time
𝑡2=
𝑚𝐿2
2𝑞𝑉
𝐾𝑖𝑛𝑒𝑡𝑖𝑐𝑘 𝐸𝑛𝑒𝑟𝑔𝑦 =
1
2
𝑚𝑣2
Electric potential Energy, a potential V = ezV
𝑚𝑣2
=2 qV 𝑣 2
=
2𝑞𝑉
𝑚
𝑣2
=
𝐿2
𝑡2
𝑡2
𝐿2 =
𝑚
2𝑞𝑉
q is the total charge = ze
Ions separation was accomplished by 1st electric acceleration, then separated based on their different flight
times/ velocities according to their m/z, in an free-field region.
Therefore, a pulsed ionization was firstly a mandatory ionization mode (specific start the ion
acceleration/extraction).
𝐿𝑖𝑛𝑒𝑎𝑟 𝑇𝑂𝐹

variations in the Kinetic E/ velocity of extracted ions (of same m/z) using Laser-Desorbed Ions
Corrected by
Delayed pulsed
extraction
Reflectron
1 st
2 nd Faster ions will move deeply (takes longer time)
than slower ions
𝑅𝑒𝑓𝑙𝑒𝑐𝑡𝑟𝑜𝑛 𝑇𝑂𝐹

𝑂𝑟𝑡ℎ𝑜𝑔𝑜𝑛𝑎 𝑎𝑐𝑐𝑒𝑙𝑒𝑟𝑎𝑡𝑜𝑟 𝑇𝑂𝐹, 𝑟𝑒𝑑𝑢𝑐𝑒 𝑡ℎ𝑒 𝑑𝑖𝑠𝑝𝑒𝑟𝑠𝑖𝑜𝑛 𝑜𝑓 𝑖𝑜𝑛 𝑣𝑒𝑙𝑜𝑐𝑖𝑡𝑖𝑒𝑠(OA)
Duty cycle (ion used ratio (from orthogonal to flight tube) was very low.
Ions loss in the orthogonal (OA) accelerator and before entering the flight tube where time required
for the ion beam to ﬁll the orthogonal accelerator is lower than that required for the ions to ﬂy in flight
tube.
Ions blocked/stored by a
slot (G1-G2), then pulsed
orthogonal to TOF.
𝐸𝑛𝑎𝑏𝑙𝑖𝑛𝑔 𝑡ℎ𝑒 𝑐𝑜𝑛𝑡𝑖𝑜𝑜𝑢𝑠
𝑖𝑜𝑛𝑖𝑠𝑎𝑡𝑖𝑜𝑛 𝑝𝑟𝑜𝑑𝑢𝑐𝑡𝑖𝑜𝑛
RF multipole ion guide (ion
optics before the accelerator )
Can further damping/ cooling
the ions and reduce their energy
dispersions.

QqW-TOF
https://doi.org/10.1007/s13361-017-1742-8

Linear Quadrupole
Ion cyclotron
Time-of-Flight
Magnetic and Electromagnetic
A mass filter based on stabilizing the ion
motion radially (X and Y) under DC and AC
𝑡2
=
𝑚𝐿2
2𝑞𝑉
A high resolution mass/ charge, separate ions
based on their time to flight a specific pass
A high resolution mass/ charge, separate ions based
on their momentum under magnetic field
𝑚
𝑒
=
𝑧𝐵2𝑟2
2𝑉
𝑣
2𝑝𝑖𝑟
=
𝑧𝐵
2𝑝𝑖𝑚
based on their cyclotron frequencies with the
magnetic field and AC
Orbitrap
based on their axial oscillations in a specific
electrostatic fields (Orbitrap).

The commonly used ion traps
Ion trap
3 D Quadrupole ion trap
Linear Quadrupole ion trap
DC and RF
Paul
Orbitrap
Ion cyclotron
Electrostatics
Penning DC and magnetic field
AC and magnetic field
http://joyreactor.com/post/693876

Videos
References
AutoVectis Suite - Mass Spectrometry,
https://www.youtube.com/watch?v=WmOAFXHFtt0&t=42s .
• E. Hoffmann, V. Stroobant, Mass spectrometry Mass spectrometry, 2016.
• O.D.S. J. THROCK WATSON, Introduction to mass spectrometry, (2019).
• J.H. Gross, Mass spectrometry Mass spectrometry, 2016.

Thank You
https://confidentkidsspeechtherapy.com/
A. Prof. Sherif M. Taha
Tel: 01004724944
sherif2taha@gmail.com

Mass spectrometry, Ion motion in the commonly used mass analyzer.pdf

Empfohlen

Empfohlen

Weitere ähnliche Inhalte

Was ist angesagt?

Was ist angesagt? (20)

Ähnlich wie Mass spectrometry, Ion motion in the commonly used mass analyzer.pdf

Ähnlich wie Mass spectrometry, Ion motion in the commonly used mass analyzer.pdf (20)

Kürzlich hochgeladen

Kürzlich hochgeladen (20)

Mass spectrometry, Ion motion in the commonly used mass analyzer.pdf