2.5 Mass Spectrometry
37
2.5 Mass Spectrometry
37
Various adducts may be formed with soft ionization methods (chemical ionization,
ESI, MALDI):
2.5.9 Homologous Mass Series as Indications of Structural Type
Certain sequences of intensity maxima in the lower mass range and the masses of
unique signals are often characteristic of a particular compound type. The intensity distribution of such ion series is in general smooth. Therefore, abrupt changes
(maxima and minima) are of structural significance. The ion or ion series most
indicative of a particular compound type is set in italics.
Mass
values, m/z
Elemental
composition
Compound types
12 + 14n
C n H 2n-2
alkenes, monocycloalkanes, alkynes, dienes,
cycloalkenes, polycyclic alicyclics, cyclic alcohols
13 + 14n
C n H 2n-1
alkanes, alkenes, monocycloalkanes, alkynes,
dienes, cycloalkenes, polycyclic alicyclics,
alcohols, alkyl ethers, cyclic alcohols, cycloalkanones, aliphatic acids, esters, lactones, thiols,
sulfides, glycols, glycol ethers, alkyl chlorides
C n H 2n-3 O
cycloalkanones
14 + 14n
C n H 2n
alkanes, alkenes, monocycloalkanes, polycyclic
alicyclics, alcohols, alkyl ethers, thiols, sulfides,
alkyl chlorides
C n H 2n-2 O
cycloalkanones
15 + 14n
C n H 2n+1
alkanes, alkenes, monocycloalkanes, alkynes,
dienes, cycloalkenes, polycyclic alicyclics,
alkanones, alkanals, glycols, glycol ethers, alkyl
chlorides, acid chlorides
C n H 2n-1 O
alkanones, alkanals, cyclic alcohols, carboxylic
acid chlorides
[M+H] +
M + 1
[M+Li] +
M + 7
[M+NH 4 ] +
M + 18
[M+H+H 2 O] +
M + 19
[M+Na] +
M + 23
[M+H+CH 3 OH] +
M + 33
[M+K] +
M + 39
[M+H+CH 3 CN] +
M + 42
[M+H+H 2 O+CH 3 OH] +
M + 51
[M+Na+CH 3 CN] +
M + 64
[2M+H] +
2M + 1
[2M+Na] +
2M + 23
[2M+K] +
2M + 39
[3M+Na] +
3M + 23
[3M+K] +
3M + 39