Heat flux Differential Scanning Calorimetry (DSC) diagram Working principles of Heat Flux DSC Advantages and disadvantages of HEAT FLUX DSC labelled diagram showing Matrix-Assisted Laser Desorption-Ionization (MALDI) Working principle of MALDI Advantages and disadvantages of MALDI Labelled Diagram of FAB .Working principle of FAB (Fast Atom Bombardment) Advantages and Disadvantages of FAB Conclusion Labelled Diagram Of continuous- dynode electron multiplier diagram .Working principle Of continuous- dynode electron multiplier continued Advantages and disadvantages of continuous- dynode electron multiplier Labelled diagram of Faraday Cup Collector Working principle of Faraday Cup Collector Advantages and disadvantages of Faraday Cup Collector References

1. Mass Spectrometry
&
Thermal Methods of Analysis
1

2. 2
• Heat flux Differential Scanning Calorimetry (DSC) diagram
• Working principles of Heat Flux DSC
• Advantages and disadvantages of HEAT FLUX DSC
• labelled diagram showing Matrix-Assisted Laser Desorption-Ionization (MALDI)
• Working principle of MALDI
• Advantages and disadvantages of MALDI
• Labelled Diagram of FAB
• .Working principle of FAB (Fast Atom Bombardment)
• Advantages and Disadvantages of FAB
• Conclusion
• Labelled Diagram Of continuous- dynode electron multiplier diagram
• .Working principle Of continuous- dynode electron multiplier continued
• Advantages and disadvantages of continuous- dynode electron multiplier
• Labelled diagram of Faraday Cup Collector
• Working principle of Faraday Cup Collector
• Advantages and disadvantages of Faraday Cup Collector
• References
CONTENT SLIDE NO
3
4-5
6
7
8-9
10
11
12-13
14
15-16
17
18-19
20
21
22-23
24
25

3. (i) Heat flux Differential Scanning Calorimetry (DSC) diagram
3

4. In heat-flux DSC, the temperature of the sample is increased at a constant rate, then
measure the temperature difference in the heat flow to the sample and reference
In this type of DSC the sample and the reference have the same heating unit, Heat
flows into both the sample and reference material via an electrically heated constant
an thermoelectric disk,
The sample and the reference is put on aluminum pans, which are sitting on top of the
thermoelectric disk.
Which is used as a path of heat flow to both the sample and the reference
The small change in heat flow to the sample and reference is monitored
by Chromel-constantan area thermocouples formed by the junction between the
constantan platform and Chrome! disks attached to the underside of the platforms.
4

5.  We find out that differential heat flow into the two pans is directly
proportional to the difference in the outputs of the two thermocouple
junctions.
 The sample temperature is estimated by the Chromel-alumel junction under
the sample disk.
………principles of the Heat flux DSC continued
5

6. A heat flux instrument cannot achieve the rapid scan rates
The temperature range is very narrow
 very high sensitivity
It is suitable to determine phase transitions like
intermediate phases between solid and liquid in Liquid
crystals
6

7. (i) labelled diagram showing Matrix-Assisted Laser Desorption-Ionization (MALDI)
7

8. Matrix-assisted laser desorption-ionization (MALDI) spectrometry is an
ionization method that can be used to obtain accurate molecular mass
information of large compounds such as polymers
It is a three step process, where the first step, a low concentration of the
analyte is uniformly dispersed in a solid or liquid matrix deposited on the
end of a stainless steel probe or placed on a metal plate.
A Matrix is just a non volatile chemical protection environment which can
be DBA, sinaptic acid etc.
 Then the plate is then placed in a vacuum chamber and a laser beam is
irradiated onto the sample which is mixed with the appropriate matrix.
The MALDI matrix must strongly absorb the laser irradiation.
8

9. ……..Working principle of MALDI continued
9

10. Advantages Disadvantages
One of the advantage is low-
cost in supplies and technician
processing time
Also Ionizes low volatility, high
mass analytes.
It has low analytical sensitivity
 Use a special type of mass
analyzer that is compatible with
pulsed ionization techniques.
10

11. 11

12. The analyte is mixed with an non volatile chemical protection environment called
matrix, the samples must be in condensed state.
This ionization technique is done by bombardment with high energetic atoms such
as argon or Xenon.
Both positive and negative analyte ions are sputtered from the surface of the sample
in a desorption process
 This treatment provides very rapid sample heating, which reduces sample
fragmentation.
12

13. The liquid matrix helps to reduce the lattice energy, which must be overcame to desorb an
ion from a condensed phase, and reduces the damage induced by the bombardment.
Matrix that can be used include glycerol, m-nitrobenzyl alcohol, crown ethers (18-crown-
6),diethanolamme,etc
FAB is considered as the soft ionizing technique and the ionizing agents in FAB are atomic
beams
….Working principle of FAB (Fast Atom Bombardment) continued
13

14. ADVANTAGES DISADVANTAGES
 It is a simple process or requires
less expertise.
Can be used in organometallics
compounds and other high mass
compounds
The analyte that we use needs
to be soluble in the matrix
that we will be using
It is not too much sensitive
14

15. CONCLUSION
The two ionization technique which is MALDI and FAB may seem confusing and
similar to each other but in reality this is not the truth, they have different
working principle
One of their difference is that in MALDI we require the use of laser light to
ionize the sample and matrix mixture
Whereas by using FAB we only require the use of atom gun with high energetic
atoms such as xenon and argon to bombard and ionize the mixture of the
sample and matrix
Another difference is that in MALDI we require a special type of mass analyser
usually TOF and In FAB no specific mass analyser used.
15

16. Conclusion of Question 2 Continued
They also differ according o the type of Matrix used, in FAB we use a solid crystalline
matrix whereas in MALDI we use a liquid matrix
Lastly they differ with sensitivity, FAB is said to be 1000 times less sensitive as compared
to MALDI
16

17. Labelled Diagram Of continuous- dynode electron multiplier diagram
17

18. The basic principle of operation is called secondary emission ,
which can be defined as a phenomenon where primary
incident particles of sufficient energy, when hitting a surface or
passing through some material, induce the emission of
secondary particles.
 A continuous dynode electron multiplier is a curve vacuum
tube that is made up of glass, impregnated with lead as to
cause resistance between the anode and the cathode .
Which in it there's a continuous voltage drop along the tube to
cause acceleration of electrons,
It must be curve in nature as to make sure that there is
secondary electron emission by the accelerated electrons in
the curvature 18

19. …..Working Of continuous- dynode electron multiplier continued
In this type of electron multiplier a primary ion when it strikes the dynodes on the interior
surface of the tube , it produces secondary electrons which are accelerated to higher-voltage
points further along the tube. As to generate more secondary electrons
The type and number of produced secondary ions matches the primary ion which struck the
surface, its energy and characteristic of the incident surface.
So by knowing the number of emitted secondary ions, we can determine the number of special
types of the ion that reached the surface.
19

20. Advantages Disadvantages
 This type of electron multiplier uses
higher voltage , which may increase
the costs of using it.
Has enhanced sensitivity and
extended operational life due
to increased surface area.
Low noise Must be shielded from external
magnetic and electric fields.
20

21. 21

22. Faraday Cup uses a prince that says when a beam or packet of ions, hits the metal, it
gains a net charge while neutralizing all other ions.
When we discharge the metal, we can the measure the small amount of imping ions
Looking at its design, it is conductive cup that is made so that it can catch particles in a
vacuum, then measure the resulting current
By measuring the current , we can then be able to count the number of electrons
hitting up the cup, as current is defined to be the flow of negative charges called
electrons.
 The instrument has hollow conducting electrode connected to ground through a high
resistance, this is called earthing. 22

23. The ions which hits the collected they trigger electron flow to the ground via
the resistor
This electrode is surrounded by cage that prevents the escape of reflected
ions and ejected secondary electrons.
The Magnetic field repellor plate reduces secondary electron loss to a few
hundred parts per million or less.
Another feature Is that Ions can also enter the cup and be reflected without
giving up their charge, a positive plate can be placed in front of the negative
repellor to reflect back these ions
…..Working principle of Faraday Cup Collector Continued
23

24. Advantages Disadvantages
Faraday Cup has low sensitivity due
to the current induced in the circuit
by ion beam are very small.
The Faraday cup collector
detection limit is limited by the
quality of the amplifier and the
thermal noise in the resistor.
This instrument has high
accuracy that is as result of
the direct relation of the
measured current and the
number of ions
 This is simple to construct and
use, also the Signals from this
collectors are stable and
reproducible
24

25. BOOKS
Michael E. Brown, Handbook Of Mass spectroscopy: Principles and
Practice, Elsevier 1998
Khatri Neetu et al. IRJP 2012, 3 (10). iNTERNATIONAL RESEARCH
JOURNAL OF PHARMARCY, ISBN NO 2230 –8407
Skoog D. A.; F James Holler. Principles of Instrumental Analysis
, 6th Edition, Thomson Learning, Inc, ISBN-13: 978-0-495-01201-6
4. WINEFORNDER J.D and al, Treatise on analytical chemistry, 2nd edi,
vol.13 pt 1993
Links/ Websites
http://site.iugaza.edu.ps/nashgar/files/2017/01/MS-Lecture-4-pdf.pdf6.
25