System and method for performing tandem mass spectrometry analysis

A system for performing tandem mass spectrometry (MS/MS) analysis of a sample includes a mass spectrometer and a processor. The mass spectrometer is configured to perform a mass spectrometry (MS) scan of an ionized sample to provide a mass of an observed peak corresponding to a precursor ion. The processor is configured to perform operations including determining whether the mass of the observed peak matches a mass of at least one of multiple expected peptides on a dynamic watch list, where the expected peptides correspond to a protein in the sample, and calculating a score of an accuracy of the determination when the mass of the observed peak is determined to match the mass of at least one of the plurality of expected peptides. The precursor ion is excluded from an MS/MS scan when the accuracy score indicates that the determination is accurate.