Mass Analyser

MASS ANALYZER
BY:- VARUN GIRME

Mass analyzer is also called ion separator.
Mass analyzer is the Heart of the mass spectrometer that
takes ionized masses and separates them based on charge to
mass ratios.
 Mass analyzer must posses the following characteristics.
I.It should have a high resolution.
II.It must have a high rate of transmission of ions.

TYPES OF MASS ANALYZERS
Quadrupole mass analyzer
Time of flight analyzer (TOF)
Magnetic sector mass analyzer
Single focusing
Double focusing
Quadrupole ion trap mass analyzer
Ion cyclotron resonances

It consists of 4 voltage carrying rods.
The ions are pass from one end to another end
During this apply the radiofrequency and voltage complex
oscillations will takes place.
Here the single positive charge ions shows the stable
oscillation and the remaining the shows the unstable
oscillations
Mass scanning is carried out by varying each of the rf and
voltage frequencies ratios keeping their ratios constant.
◦Quadrupole ion storage (ion trap)
◦It store the unsorted ions temporarily, they released to the
detector by scanning the electric field.

Advantage:
 Classical mass spectra.
 Good reproducibility.
 Relatively small and low-cost systems.
 Limitations:
 Limited resolution.
 Peak heights variable as a function of mass.
 Not well suited for pulsed ionization methods.

Application:
In GC/MS and LC/MS systems.
Triple quadrupole MS/MS systems.
Bimolecular detection.

2.TIME OF FLIGHT MASS ANALYZER
(TOF)
In this type of analyzer the sorting of ions is done in absence
of magnetic field.
The ions produced are acquiring different velocities
depending on their masses
Here the particles reach the detector in the order of the
increasing order of their masses
 Here electron multiplier detector is used.
The resolution power of this is 500-600

ADVANTAGES
 Theoretically unlimited mass range.
 Moderate to high resolving powers .
 Moderate cost .
 Relatively high duty cycle.
 Instrument is not scanning.

3.MAGNETIC SECTOR MASS ANALYZER
Single Focusing Magnetic Mass Analyzer

It has horse shoe shaped glass tube which is evacuated,
consists of sample inlet, electron bombarding source,
accelerating plates on one end,& collector slit at other end.
At curvature of tube there is provision to apply
electric/magnetic field
Sample in the form vapour is allowed through inlet and
bombarded with electron beam at 70eV.
It knocks off one electron from every molecule then they
become +vely charged ion.
As these molecules become +ve charged, they are
accelerated by accelerating plates and travel in straight path.

By application of electric or magnetic field they travel in
curved path & molecular ions are separated according to
their masses and collected.
Different fragments fall on detector then mass spectrum is
recorded.

Double Focusing Magnetic Mass Analyzer

It is used differentiate the small mass differences of the
fragment.
These provides the high resolution
To achieve better focusing, energy has to be reduced before
ions are allowed to enter the magnetic field and increase
resolving power can be obtained two mass analyzers in series.
 In a double-focusing mass analyzer beam is first passes
radial Electrostatic field.
Advantages:
Classical mass spectra.
Very high reproducibility.
High resolution.
High sensitivity.
High dynamic range.
.

Limitations:
Not well-suited for pulsed ionization methods (e.g. MALDI).
 Usually larger and higher cost than other mass analyzers.
Applications:
All organic MS analysis methods.
Accurate mass measurement.
Isotope ratio measurements.

4.QUADRUPOLE ION TRAP MASS
ANALYZERS
There are two principal ion trapped mass analyzers
Three- dimensional quadrupole ion traps ("dynamic" traps),
and ion cyclotron resonance mass spectrometers
("static" traps).
Both Operate by storing ions by using DC and RF electric
fields.

5.ION CYCLOTRON RESONANCES
Ions in a magnetic field move in circular orbits characteristic
of their m/z values.
If energy is provided at a frequency equal to their precession
frequency, and in a direction perpendicular to their plane of
precession,
Ions will absorb the energy, enabling them to be detected.

Advantage :
 The highest recorded mass resolution of all mass
spectrometers.
 Powerful capabilities for ion chemistry and MS/MS
experiments.
 Well-suited for use with pulsed ionization methods such as
MALDI.
 Non-destructive ion détection; ion remesurèrent.
 Stable mass calibration in superconducting magnet FTICR
systems.

Limitations:
Limited dynamic range.
Strict low-pressure requirements mandate an external
source for most analytical applications.
Subject to space charge effects and ion molecule
reactions.
Applications:
Ion chemistry.
High-resolution electrospray experiments for high-mass
analytes.
Laser desorption for materials and surface
characterization.

Mass Analyser

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