Charge changes, tandem mass

Tandem mass spectrometry, abbreviated MS/MS, is any general method involving at least two stages of mass analysis, either in conjunction with a dissociation process or in a chemical reaction that causes a change in the mass or charge of an ion [1-3]. 

Apart from the endoergic dissociation reactions mentioned above, a variety of other reactions can also be accessed in tandem mass spectrometry. In many such reactions, collectively termed charge-permutation reactions, there is a change in the charge of the colliding species during the collision-activation step. Some of the reactions are discussed here. For further reading, an excellent review on the subject can be consulted [32]. 

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