Mass Losses on Fragmentation

When a molecule ionizes it follows the reaction M + e M + e + e, as described earlier. When an odd electron molecular ion fragments it can do so in variety of ways, and resulting odd electron fragment ions can also fragment in similar ways. Simple cleavage results in the expulsion of a neutral fragment that is an odd electron radical (OE ) and formation of an even electron ion (EE ) as shown  

Multicentered fragmentation results in the expulsion of an even electron neutral species (EE) and formation of an odd electron ion (OE )  

In the first case we would detect the EE ion and in the second case the OE ion. The neutral species lost on fragmentation can be identified by the difference between the mass of M and the fragment ion. Common losses from the molecular ion are given in Table 10.9. Tables 10.10 and 10.11 list more common neutral fragments expelled by simple cleavage and by multicentered fragmentations. 

---