102 Mass Spectroscopy
A mass spectroscope measures the exact mass of ions, relative to the charge. Many times,
some form of seperation is done beforehand, enabling a spectrum to be collected on a
relatively pure sample. An organic sample can be introduced into a mass spectroscope and
ionised. This also breaks some molecules into smaller fragments.
The resulting mass spectrum shows:
The heaviest ion is simply the ionised molecule itself. We can simply record its mass.
Other ions are fragments of the molecule and give information about its structure. Com-
mon fragments are:
species formula mass
methyl CH 3 + 15
ethyl C 2 H 5 + 29
phenyl C 6 H 5 + 77