Analyser of Quadrupole and time of flight.Mass Analysers. Summary of Mass Analyser. Quadrupole mass spectrometer. Factors Affecting Function Of Quadrupole. Principal, Construction & Working. Linear Time of flight mass spectrometer. Time Of Flight Mass Spectrometry, Need For Variant Type Of Time of Flight Analyser. Variant Of Linear TOF Analyser. Ion mirror / ion reflectron / reflectron. Time-lag focussing. Advantages, Disadvantage, Application.

1. Analyser of Quadrupole and
time of flight
Presented By -
Nishinandan R. Suryawanshi
Roll No - 5006
Guided By –
Dr. Vivek B. Panchabhai
Channabasweshwar college of pharmacy,
Latur

2. Contents :
 Introduction
 Principle
 Theory
 Construction & Working
 Variants
 Advantages
 Disadvantages
 Applications

3. Introduction
Mass spectroscopy is an analytical chemistry
technique that helps to identifying the
amount & type of chemicals present in a
sample by measuring the mass-to-charge
ratio and abundance of gas phase ions.
Define:
A type of mass spectrometry where
the mass-to-charge ratio of the sample ions
is measured whilst the ions are held in a
stable orbit by an electric field generated by
four parallel electrodes.

5. Mass Analysers
 Mass analyzers are called heart of mass
spectrometer.
 These are the instrument which separate
the mixture of ions that are generated
during the ionization step by m/z in order
to obtain a spectrum.

6. Types of mass analysers
 Magnet sector mass spectrometer
 Quadrupole mass spectrometer
 Ion trap mass spectrometer
 Time of flight mass spectrometer
 Fourier transform mass spectrometer

7. Summary of mass analysers
Mass Mass Range Resolutio
n
Sensiti
vity
Magnetic sectot 1-15000 m/z 0.0001 Low
Quadrupole 1-5000 m/z Unit High
Ion trap 1-5000 m/z Unit High
Time of flight Unlimited 0.0001 High
Fouriier
transform
Up to 70k
Da
0.0001 High

8. Quadrupole mass spectrometer
 Quadrupole mass analysers concept was
first reported by Paul and Steinwedel in the
1950s.
 Quadrupole consists of four rods which are
arranged parallelly.
 Rods opposite to one another are
electrically connected.
 Ions are separated based on m/z at a
particular DC and Radiofrequency voltage.

9. Principle
 Ions from the ions sourcw
 Quadrupole analyser with a constant DC
& RF voltage
 At given combination of DC & RF
voltage
 Ions with certain m/z values reach the
detector
 Ions with different m/z values travel
unstable path

10. Principle

11. Construction
 It consists of four electrically conducting
parallel rods.
 One diagonally opposite pair of rods is
held at +Udc volts and the other pair at –
Udc volts.
 A radiofrequency oscillator supplies
+Vcosωt to the first pair and –Vcosωt to
the second pair.
 Ions enter to the quadrupole through a
circular aperture.

13. Ex.
 CO2 molecules have
quadrupole–quadrupole
interactions with each other.
 The central carbon carries a
partial positive charge, while
the terminal oxygens carry
partial negative charges.
 The like-charge atoms have
repulsive electrostatic
interactions (+/+ and -/-)
while the oppositely-charged
atoms have attractive
electrostatic interactions
(+/-).

14. FACTORS AFFECTING
FUNCTION OF QUADRUPOLE:
 Focussing slits
 Rod length
 Rod diameter
 Increased RF frequency

15. ADVANTAGES:
 High sensitivity.
 They can operate close to ground potential.
 Ideal for interfacing to LC system and for
atmospheric pressure ionization (API)
techniques such as electrospray.
 Well suited for the negative ions ,since the
analyser does not discriminate between the
polarity of the ions.
 Economic, robust and scanning is very fast

16. DISADVANTAGES:
 Quadrupole is generally inferior to
magnetic sector analyser with respect to
resolution and mass range.
 Peak height variable as a function of
mass.
 Not well suited for pulsed ionization
methods.

17. APPLICATIONS
 In liquid chromatography-Mass
spectrometry.
 In Gas chromatography-Mass
spectrometry.
 To measure the relative amounts of
different gases in a mixture.
 Proteomics.

18. TIME OF FLIGHT MASS
SPECTROMETR
Introduction :-
 Stephens first described the concept of
time of flight in 1946.
 As the name implies, time of flight mass
spectrometer separates ions and measure
their m/z based on the time they take to
pass
( “fly” ) from the ion source to the
detector.

19. PRINCIPLE
 Ions with different masses and same
kinetic energy travel when accelerated and
the ions with smaller masses (less m/z
value)reaches early to the detector than
the bigger masses .

20. THEORY
The kinetic energy of ions of mass (m), charge (z)
and accelerating potential (V) is given by
KE = zV = ½ mv2 (1)
Where (v) is velocity of the ions which is given by
v = l/t
where, l = length of the tube
t = time taken by the ions to pass the length of the
tube
Therefore, equation 1 becomes
zV = ½ ml2/t2
m/z = 2Vt2/l2
2V/l2 = k (constant)
therefore, m/z = kt2
m/z α t2

22. Working
IONS FROM THE ION SOURCE
//
TOF
//
ACCELERATION OF IONS
//
ACQUIRES DIFFERENT VELOCITIES
//
SPATIAL SEPARATION OF IONS IONS
//
WITH HIGHER VELOCITY REACH THE
DETECTOR FIRST

23. NEED FOR VARIANT TYPE OF
TOF ANALYSER
 Ions with very similar m/z ratio may have
relatively poor mass resolutions .
 This is due to the spatial distribution in
the ion source and their proximity to the
applied electric field, not all the ions
receive the same kinetic energy.
 This leads to components in mixtures
being unresolved from one another and
large errors in molecular weight
measurements.

24. VARIANTS OF LINEAR TOF
ANALYSER
1. Ion mirror / ion reflectron / reflectron.
For ex. Consider two ions of the
same m/z ratio that having slightly
different kinetic energy.

25. 2. Time-lag focussing
 In time-lag focusing TOF applying
accelerating potential is delayed.
Ions from the ion source will have some
kinetic energy and moves with different
velocities
Application of potential gives more
energy to the ions which are away from
the detector than closer to it.
The amplitude is adjusted in such a way
that all the ions reach the detector at the
same time.

26. ADVANTAGES
 Mass range is unlimited.
 Excellent sensitivity due to lack of
resolving slits.
DISADVANTAGES
 Limited use in case of pulsed ionization
techniques.
 Mass resolution is usually less than 20000.
 Fast electronics are necessary for adequate
resolution.

27. APPLICATION
 Due to its fast scanning capability it is
increasingly being used in LC-MS
instrumentation.
 Generally it is used in case of fast analysis
or in high chromatographic resolution
techniques.

28. REFERENCE
 Spectrometric identification of organic
compounds by Robert M Silverstein and
Francis X Webster,pg. no. 10-12.
 Instrumental methods of analysis ,7th
edition by Willard Merrit Dean Settle, pg.
no. 480-483.