A system for compound identification using multiple spectra that are a function of collision energy, comprising: a mass spectrometer that is configured to analyze a sample and within each cycle of the mass spectrometer to select at least one ion and to fragment the at least one ion using two or more collision energies, producing a plurality of acquired fragment ion spectra that are a function of collision energy; a database of known compounds that includes for each known compound a plurality of fragment ion spectra that are a function of collision energy; and a processor in communication with the mass spectrometer and the database that is configured to: receive the plurality of acquired fragment ion spectra for the at least one ion from the mass spectrometer, calculate one or more sample fragment ion rates of change of mass intensity, with respect to collision energy, for one or more sample fragment ions from the plurality of acquired fragment ion spectra calculate one or more database fragment ion rates of change of mass intensity, with respect to collision energy, for one or more database fragment ions of one or more known compounds in the database, and compare the one or more sample fragment ion rates of change of mass intensity with the one or more database fragment ion rates of change of mass intensity to identify the at least one ion. a mass spectrometer that is configured to analyze a sample and within each cycle of the mass spectrometer to select at least one ion and to fragment the at least one ion using two or more collision energies, producing a plurality of acquired fragment ion spectra that are a function of collision energy; a database of known compounds that includes for each known compound a plurality of fragment ion spectra that are a function of collision energy; and a processor in communication with the mass spectrometer and the database that is configured to: receive the plurality of acquired fragment ion spectra for the at least one ion from the mass spectrometer, calculate one or more sample fragment ion rates of change of mass intensity, with respect to collision energy, for one or more sample fragment ions from the plurality of acquired fragment ion spectra calculate one or more database fragment ion rates of change of mass intensity, with respect to collision energy, for one or more database fragment ions of one or more known compounds in the database, and compare the one or more sample fragment ion rates of change of mass intensity with the one or more database fragment ion rates of change of mass intensity to identify the at least one ion. receive the plurality of acquired fragment ion spectra for the at least one ion from the mass spectrometer, calculate one or more sample fragment ion rates of change of mass intensity, with respect to collision energy, for one or more sample fragment ions from the plurality of acquired fragment ion spectra calculate one or more database fragment ion rates of change of mass intensity, with respect to collision energy, for one or more database fragment ions of one or more known compounds in the database, and compare the one or more sample fragment ion rates of change of mass intensity with the one or more database fragment ion rates of change of mass intensity to identify the at least one ion.