Stable fragments in the mass spectrum:

In addition to the common fragmentation patterns discussed above, the origin of a number of peaks in the mass spectrum can be explained in terms of loss of small stable neutral molecules like H₂, NH₃, CO, H₂S, alcohols and alkenes etc.  These however, are not being taken up here. You might look into any standard text on Organic Spectroscopy for the same.

Some commonly lost fragments and the stable fragments observed in the mass spectrum are compiled in Table. These would be useful when you attempt to use the mass spectral data for the structure elucidation of the molecules.

Table: Some commonly lost fragments and the stable fragments in the mass spectrum