Illustrated Glossary of Organic Chemistry
M:
In
mass spectrometry
the
molecular
ion
composed of
isotopes
with the lowest mass numbers, such as
1
H
(mass = 1
amu
) instead of
2
H
(
deuterium
; mass = 2
amu
) and
12
C
(mass = 12
amu
) instead of
13
C
(mass = 13
amu
).
Molecular ion
region of the
mass spectrum
of 1-chloro
decane
(C
10
H
21
Cl).
The
relative abundance
of M is due to
12
C
10
1
H
21
35
Cl.
The
relative abundance
of
M+1
is due to
12
C
9
13
C
1
H
21
35
Cl +
12
C
10
1
H
20
2
H
35
Cl.
The
relative abundance
of
M+2
is due to
12
C
9
14
C
1
H
21
35
Cl +
12
C
8
13
C
2
1
H
21
35
Cl +
12
C
9
13
C
1
H
20
2
H
35
Cl +
12
C
10
1
H
19
2
H
2
35
Cl +
12
C
10
1
H
19
3
H
35
Cl +
12
C
10
1
H
21
37
Cl.
Related terms:
Radical cation
,
nitrogen rule
,
fragmentation
,
base peak
,
m/z
,
nominal mass
,
high-resolution mass spectrometry
,
exact mass
,
electron impact ionization
,
EI
,
chemical ionization
,
CI
,
MALDI
,
gas chromatography-mass spectrometry
,
GC-MS
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