Transcript Thermospray ionization - Seton Hall University

LC-MS
Lecture 7
LC-MS
LC
Interface
Mass
Analyzer
Detector
Extraction of
Ion evaporation
The analyte from or ionization.
The solvent
Fragmentation
 LC – Separation of the mixture of analytes
 Interface – Separation of the analyte from the solvent
 MA (mass analyzer) – separation of the analyte molecular
ion and fragments according to their mass to charge ratio
PROBLEMS IN COMBINING
HPLC AND MS
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HPLC
Liquid phase operation
25 - 50 deg. C
No mass range
limitations
Inorganic buffers
1 ml/min eluent flow is
equivalent to 500 ml/min
of gas
MS
 Vacuum operation
 200 - 300 deg. C
 Up to 4000 Da for
quadrupole MS
 Requires volatile buffers
 Accepts 10 ml/min gas
flow
Interface
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Historical
Moving belt
Thermospray
Common interfaces
Electrospray
APCI
Special interfaces
Particle beam LC/MS
Continuous flow FAB
Atmospheric pressure photon ionization
MALDI
Basic Electrospray Schematic
N
760 Torr
1 Torr
10-2 –
10-5-4 Torr
Torr
10
10-5 Torr
Ion optics
Formation of gas phase ions from solution phase
Richard B. Cole, Electrospray Ionization Mass Spectrometry, Fundamentals Instrumentation and Applications, Wiley Interscience, 1997
API-Electrospray Interface (HP)
Orthogonal ESI schematic (Waters)
ZQ interface (Waters)
ELECTROSPRAY
Factors to consider
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Ionic strength
Surface tension of the solvent
Volatility of the solvent
Character of the analyte ions in solution: solvated, ion paired,
etc
Mobile phase composition and amount of water
pH of the mobile phase
APCI INTERFACE
APCI IONIZATION CHAMBER
Fragmentation
PROTEIN SPECTRUM
(multiple charge)
M
M i 1  1
M i  M i 1
M i
(M+2)/(z+2)
(M+1)/(z+1)
M/z
MASS ANALYZERS
 Quadrupole
 Ion Trap
 Time-of-Flight
 Magnetic Sector
 ICR (Ion-cyclotron resonance)
Resolution of MA
Comparison of MA
Quadrupole MA
Quadrupole MA –
Mass Filter
Only ions with the
specific M/z could
pass between rods at
set values of DC and
RF voltages
Quadrupole MA
Electromagnetic field in
Quadrupole
Ion Trap
Ion trajectory in Ion-Trap
Time-of-Flight
Bipolar TOF
Reflectron Time-of-Flight
MS-MS
TRIPLE QUADRUPOLE
MS-MS (triple quad – TOF)
Magnetic Sector
Double focusing Magnetic sector