Gelatin is a mixture of high molecular weight polypeptides from the hydrolysis of collagen.Doubly Charged Selected Ion Monitoring (DC-SIM) is the most suitable scanning mode to detect known peptides in complex samples when an ion–trap mass spectrometer is the instrument used for the analysis.In this mode,the MS detector is programmed to perform continuous MS/MS on one or more selected precursors,either during a selected time interval,or along the whole chromatographic run.MS/MS spectra are recorded,so virtual multiple reaction monitoring chromatogram traces for the different fragment ions can be plotted.In this work,a PCA method was applied to the detection of previously characterized species-specific peptides from different gelatins.The proposed methodology makes use of trypsin digestion for sample preparation,peptide separation and identification by rapid resolution liquid chromatography coupled to an ion-trap working in the auto MS2 mode.This methodology was applied to the differential classification of five commercial,homological,species of gelatins proving to be an excellent tool for gelatins product authentication,which may be used by manufacturers to provide a fast and effective identification of the gelatins,guaranteeing the quality and safety of foodstuffs to consumers.