This method identifies fragment peaks using MS/MS scan data. Fragment ions are usually produced from another, bigger ion, in the ionization source. Such additional signals represent an undesired noise.
Fragments are identified by 2 conditions: 1) the retention time of the original ion and the fragment ion should be same and 2) the MS/MS pattern of the original ion must be found in the data set and is must contain a peak with the same mass as the fragment ion.