Selected Tandem Mass Spectrometry Ion

1 Selected tandem mass spectrometry (MS/MS) ion monitoring (SMIM) is the most 2 suitable scanning mode to detect known peptides in complex samples when an ion-trap 3 mass spectrometer is the instrument used for the analysis. In this mode, the MS detector 4 is programmed to perform continuous MS/MS scans on one or more selected 5 precursors, either during a selected time interval, or along the whole chromatographic 6 run. MS/MS spectra are recorded, so virtual multiple reaction monitoring chromatogram 7 traces for the different fragment ions can be plotted. In this work, a shotgun proteomics 8 approach was applied to the detection of previously characterized species-specific 9 peptides from different seafood species. The proposed methodology makes use of high 10 intensity focused ultrasoundassisted trypsin digestion for ultra fast sample preparation, 11 peptide separation and identification by reverse phase capillary LC coupled to an ion12 trap working in the SMIM scanning mode. This methodology was applied to the 13 differential classification of seven commercial, closely related, species of Decapoda 14 shrimps proving to be an excellent tool for seafood product authentication, which may 15 be used by fisheries and manufacturers to provide a fast and effective identification of 16 the specimens, guaranteeing the quality and safety of foodstuffs to consumers. 17