This document discusses mass spectrometry techniques. It provides information on: 1) The basic principles of mass spectrometry which involve producing ions from samples and separating them based on their mass-to-charge ratio. 2) The main uses of mass spectrometry in organic chemistry which are to determine the molecular mass and formula of organic compounds from very small samples. 3) Different ionization techniques used in mass spectrometry like electron impact, electrospray, and atmospheric pressure chemical ionization. It also discusses mass analyzers and applications of mass spectrometry in various fields.

1. Prof. Dr. Sudibyo Martono, M.S., Apt.
ANALISIS
FISIKO KIMIA I

2. Spektra Massa

3. SPECTRA MS
Mass Spectrometry
The basic principles
Applications
3

4. SPECTRA MS
THE MAIN USE OF MS IN ORGANIC CHEMISTRY IS:
• DETERMINE THE MOLECULAR MASS OF ORGANIC
COMPOUNDS
• DETERMINE THE MOLECULAR FORMULA OF ORGANIC
COMPOUNDS
Mass Spectrometry
4

5. SPECTRA MS
Mass Spectrometry
• Molecular weight can be obtained from a very small
sample.
• It does not involve the absorption or emission of
light.
• A beam of high-energy electrons breaks the
molecule apart.
• The masses of the fragments and their relative
abundance reveal information about the structure of
the molecule.
5

6. SPECTRA MS
What is a mass spectrometer ?
A mass spectrometer is an instrument which
produces charged particles (ions) from
chemical substances under analysis.
It then uses magnetic and/or electric fields to
separate those ions and to measure their
mass.
6

7. SPECTRA MS 7

8. SPECTRA MS 8

9. SPECTRA MS 9

10. SPECTRA MS 10

11. SPECTRA MS
Ion Generation
~70 Volts
+
_
+
_
e- e-
e-
++ +++
+
_
Electron Collector (Trap)
Repeller
Extraction
Plate
Filament
To Analyzer
Inlet
Electrons
Neutral
Molecules Positive Ions
11

12. SPECTRA MS 12

13. APCIAPCI
SPECTRA MS 13

14. Electrospray Ionization
• Sample dissolved in polar, volatile buffer
(no salts) and pumped through a
stainless steel capillary (70 - 150 µm) at
a rate of 10-100 µL/min
• Strong voltage (3-4 kV) applied at tip
along with flow of nebulizing gas causes
the sample to “nebulize” or aerosolize
• Aerosol is directed through regions of
higher vacuum until droplets evaporate to
near atomic size (still carrying charges)
SPECTRA MS 14

15. SPECTRA MS 15

16. ESIESI
SPECTRA MS 16

17. Electrospray (Detail)Electrospray (Detail)
SPECTRA MS 17

18. Electrospray Ionization
• Can be modified to “nanospray” system
with flow < 1 µL/min
• Very sensitive technique, requires less
than a picomole of material
• Strongly affected by salts & detergents
• Positive ion mode measures (M + H)+
(add formic acid to solvent)
• Negative ion mode measures (M - H)-
(add ammonia to solvent)
SPECTRA MS 18

19. SPECTRA MS
ELECTRON IMPACT
H-C:H
H
H
+ e H-C
H
H
H + 2e
RADICAL CATION
CH4
H-C
H
H
H
H-C
H
H
+ + H
ONLY CATIONS ARE CARRIED TO DETECTOR
H-C
H
H
H++
CATION
RADICALBOND-BREAKING
19

20. SPECTRA MS
Electron Impact Ionization
A high-energy electron can dislodge an electron
from a bond, creating a radical cation (a positive ion
with an unpaired e-
).
e- + H C
H
H
C
H
H
H
H C
H
H
C
H
H
H
H C
H
H
C
H
H
+ H
H C
H
H
C
H
H
H
+
=>20

21. SPECTRA MS
SEPARATION OF IONS
• Only the cations are deflected by the magnetic
field.
• Amount of deflection depends on m/z.
• The detector signal is proportional to the
number of ions hitting it.
• By varying the magnetic field, ions of all masses
are collected and counted. =>
21

22. Positive or Negative Ion Mode ?
• If the sample has functional groups that readily
accept H+ (such as amide and amino groups
found in peptides and proteins) then positive ion
detection is used-PROTEINS
• If a sample has functional groups that readily lose
a proton (such as carboxylic acids and hydroxyls
as found in nucleic acids and sugars) then
negative ion detection is used-DNA
SPECTRA MS 22

23. SPECTRA MS
Mass Spectrometer Schematic
Ion
Source
Mass
Analyzer
Ion
Detector
Inlet Data
System
Vacuum
Pumps
Sample
Introduction
Data
Output
23

24. SPECTRA MS
The magnetic field exerts a force on these fast-
moving ions and causes them to move in a circular
path, the radius of which is dependent upon their
mass to charge ratio (m/z) and speed.
24

25. SPECTRA MS
Magnetic Mass Separation
ion not detected
m/z too large
ion not detected
m/z too small
Correct m/z ratio
ion detected
Ion
Source
Detector
S
N
Electromagnet
25

26. SPECTRA MS
Fragments appear due to bond cleavage next to C=O
(alkoxy group loss, -OR) and hydrogen rearrangements.
100
80
60
40
20
0
100806040200
mass / charge (m/z)
relativeabundance
-OCH2CH3
-C2H3
43
45 8861
CH3
O
O CH2
CH3
61
43 45
H
H
m/z(parent ion) = 88
26

27. SPECTRA MS
Typical Mass Spectrum
100%
50%
43
58
71
114
m/e
base peak given 100%
abundance
molecular ion
Isotope peaks - P+1,
P+2, etc
Alarm Pheromone of Honey Bee
Note: 114-71 = 43
Note: 43 = mass of radical
27

28. SPECTRA MS
CH3CH2CH2CHCH3
CH3
m/z 86
+
•
Facile
Facile
More difficult
CH3CH2CH2
CHCH3
CH3
+• +
m/z 43
CH3 CH3CH2CH2CH
CH3
m/z 71
+•
+
+• +
m/z 57
Fragmentation of 2-Methylpentane
CH3CH2 CH2CHCH3
CH3
28

29. SPECTRA MS
Mass Spectrum of 2-MethylpentaneIntensity
m/z
20
40
60
80
100
10 20 30 40 50 60 70 80 90
43
57
71
86, M+
CH3CH2CH2CHCH3
CH3
29

30. SPECTRA MS
Mass Spectrum of PentaneIntensity
20
40
60
80
100
10 20 30 40 50 60 70
43
57
72, M+
CH3CH2CH2CH2CH3
42
41
39
27
29
m/z 30

31. SPECTRA MS
Intensity
20
40
60
80
100
20 40 60 80 100 120 140
94
156
107
160
94
107
m/z
2-Chloroethylphenyl ether
O
Cl H
31

32. SPECTRA MS
Triple Quadrupole Mass Analyzer
Sample Inlet
Q2
(Collision cell)
Q3
Ion Guide
Q1
EM
Detector
32

33. SPECTRA MS
LC-MS-MSLC-MS-MS
33

34. SPECTRA MS
MRM
34

35. SPECTRA MS
LC
column
Q1 (227) Q2 collision cell
Fragment
parent ion
Q3 (181)
Set on mass of
parent ion
Transmit only
diagnostic
product ion
highest duty cycle triple quadrupole scan type!
OH
NH3+
NO2
O OH
OH
NH2+
NO2
Multiple Reaction Monitoring in Triple Quadrupole
35

36. SPECTRA MS
Applications
- Chemical analysis (Chemical Research
- Environmental analysis
- Analysis of petroleum products
- Trace metals
- Biological materials
Mass spectrometers are used for all kinds of
chemical analyses:
36

37. SPECTRA MS
Terima KasihTerima Kasih
E-mail: sudib_kekes@yahoo.co.id
37

38. SPECTRA MS 38