PowerPoint-presentatie

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3th EU-Meeting on Cobalamins and Mimics Antwerp -
Belgium
Introduction to Mass Spectrometry
Eddy Esmans May 2004
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NICI
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analyzers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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Inlet system
The Components of a Mass Spectrometer
m/z
Mass Spectrum
Computer
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NIC
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analysers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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II. Ionization methods
1. Electron impact
kr
E
M.
Fi.
70 eV electron
Unimolecular type
E internal energy of e.g. M.
N-1
E0 activation energy of a particular
fragmentation
kr n
N degrees of freedom
n frequency factor
IONIZATION EFFICIENCY ca. 1/1000
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QET Quasi Equilibrium Theory
b. The energy transferred to M is not
localised but is statistically spread over the
molecule.
c. If the event occurs than this energy is
concentrated at one particular bond. This bond
will break here.
d. The probability of breaking a particular
bond in not a function of abundance.
e. Metastable ions are formed ions with a
life time of gt 10-6 seconds.
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E-impact-ionisation occurs according to the
Frank-Condon-principle (vibration is 100 times
slower than ionisation)
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NICI
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analysers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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2. Chemical ionization (CI) and DCI, NICI
M(g) reagent gas MH
benefit producing molecular mass
information
proton affinity !!!
proton affinity PA of M gt proton
affinity PA of the reacting species
Classical reagent gasses Methane CH5 NH3
NH4 (NH3. NH3 NH4
NH2.) Isobutane C4H9
PS if PA(M) ? PA(reagent gas) MH
ADDUCT FORMATION
M NH4
M C2H5
if PA(M) lt PA(reagent gas)
only adducts bad sensitivity
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Desorption chemical ionization
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Negative Ion Chemical Ionization
Principle ion souce is filled with CH4 and 70
eV electrons are slowed down to
thermal energy.
These electrons can be captured by molecules
containing sulphur (cfr. Electron capture GC)
formation of M--ions
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NICI
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analysers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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Fast atom bombardment (FAB) and Secundary Ion
Mass Spectrometry (SIMS)
Ions (Cs) Neutrals (Ar, Xe, )
Principle
IONS analysed
Sample
1. FAB
Ar e Ar acceleration
(5-15 KeV)
Ar Ar Ar Ar
fast
slow
slow
8 KeV
fast
2. SIMS
Cs generated (35 KeV)
3. LSIMS
Sputtering yield (number of particles
ejected/incident particle)
Dependent on mass and velocity of impinging
particle
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Matrix properties
1. Good solubility
2. Vapour pressure must be sufficiently low to
maintain vacuum conditions
3. Viscosity must allow diffusion of the analyte
from the bulk to the surface
4. Polar to solvate and separate preformed ion
glycerol, 3-nitrobenzylalcohol, mixture
of 1,4-dithiothreitol/1,4-dithioerythitol 51
(magic bullet)
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Laser Desorption Matrix Assisted Laser
Desorption
A few lasers
N2 laser 337 nm Nd-Yag laser 354 266
nm E 20mJ/cm2
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NICI
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analysers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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Field desorption
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NICI
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analysers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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Picofrit columns

• injection 1 ml
• flow-rate 500 nl/min
• isocratic 20/80 NH4Ac (0.01 M) / MeOH
• column AQUASIL C18, 75 mm x 4.9 cm (15cm 2cm),
  tip 5 mm

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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NICI
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analyzers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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I. Ion source
Ions get kinetic energy
V ? 8 KV
V tension m mass v speed z charge
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II. Electrostatic sector
E electrostatic field
Ions with the same Ekin will travel with the same
r and leave the electrostatic sector at the same
point (This is independant of their mass !!!)
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III. Magnetic sector
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NIC
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analyzers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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a. Quadrupole filter
E E0 (?x ?y ?z)
Quadrupole field
Independent field in x,y,z-directions.
Ions entering this field will undergo a force
F eE
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Quadrupole field subjected to the restraites
imposed by the Laplace-equations
Physical meaning the Laplacean is a measure for
the distorsion
of the E-field
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Hyperbolean !!!
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Applied potential
1. Equation of motion of the ions entering this
field
mx eEx

-
mx

mx


x
xz and yz motion of ions in plane

y
mz 0

Velocity in z-direction is cte but ions are
accelerated in x and y-directions !
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Stability diagram
?0 U V.cos?t (? 2?f)

x

y
Matthieu-equations
U 500-2000 V V 0-3000 V
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Stability diagram
scanning changing U and V
but keeping
what if U 0
resolution 0
Rf-quadrupole only will be able to
pass m/z-values
gt certain m/z-value as long as V is
in stability area.
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NIC
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analyzers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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Ion cyclotron resonance Fourier Transform MS
Ion can be trapped in a H-field
The ion will have a stable trajectory when
circular motion with frequency
Relation between ? and m/z-value
each m/z-value will move with its typical
frequency/radius
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Simultaneously excite all ions by electromagnetic
pulse (1µs). Depending on their m/z-values ions
will absorb energy at their frequency and
subsequently get hifgher trajectories close to
the receive plates. All the frequencies detected
in this time ellaps by the receive plates at the
same time.
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NIC
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analyzers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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Time of Flight
Source ion
flight tube L
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Time of Flight
Reflectron corrects for energy dispension
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Time an ion spends in reflectron
correct energy E
2 ions with mass M
energy E
t, t flight time in the field free region of
TOF
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Ions come in the reflectron penetrate a
distance x or x
x a2x
Conclusion
agt1 EkingtEkin
tflightlttflight but x gt x
alt1 Ekinlt Ekin
tflightgttflight but x lt x
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Tandem Mass Spectrometry
MP MF
penetration depth
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Time in reflectron to penetrate a distance n
Total time in reflectron to cover a distance of 2x
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I. Introduction
II. Ionization methods
1. Electron impact
2. Chemical ionization and DCI, NIC
3. FAB, SIMS, LD and MALDI
4. Field desorption
5. Electrospray ionization
III. Analyzers
1. Magnetic sector
2. Quadrupole ion trap
3. Fourier transform
4. Time of flight
IV. MS/MS-methods
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