Tandem mass spectrometry, also known as
MS/MS or
MS2, involves multiple steps of
mass spectrometry selection, with some form of fragmentation occurring in between the stages. In a tandem mass spectrometer,
ions are formed in the
ion source and separated by
mass-to-charge ratio in the first stage of mass spectrometry (MS1). Ions of a particular mass-to-charge ratio (precursor ions) are selected and
fragment ions (product ions) are created by
collision-induced dissociation, ion-molecule reaction,
photodissociation, or other process. The resulting ions are then separated and detected in a second stage of mass spectrometry (MS2).