Selected reaction monitoring
![In selected reaction monitoring, the mass selection stage MS1 selects precursor ions that undergo fragmentation followed by product ion selection in the MS2 stage. Additional stages of selection and fragmentation can be performed.](/Images/godic/202502/10/MS_MS2254.png")
Selected reaction monitoring (SRM) is a method used in tandem mass spectrometry in which an ion of a particular mass is selected in the first stage of a tandem mass spectrometer and an ion product of a fragmentation reaction of the precursor ion is selected in the second mass spectrometer stage for detection.