Characteristics of a mass spectrum:

The mass spectrum gives a plot of the intensities (proportional to the amounts) of different fragments as a function of their m /z values. The most intense peak in the spectrum is given an intensity of 100 and is called the base peak; the intensity of other peaks is given with respect to the base peak in fragmentation pattern.  Another characteristic of the spectrum is the presence of peaks called isotopic peaks, observed due to the natural abundance of the isotopes of constituent atoms of a molecule.

The isotopic peaks in a mass spectrum refer to the peaks observed at m/ z values greater than the molecular ion peak. These arise due to the natural abundance of the isotopes of constituent atoms of a molecule. These are useful in the determination of the molecular formula of the compound. These may also be used for the determination of the accurate masses of the isotopes.