A method of extracting a mass trace from mass spectrometry data of a mass stream emitted from a separation device as a function of a separation parameter, the method comprising, receiving the mass spectrometry data, wherein the mass spectrometry data comprise a plurality of mass spectra each obtained for respective values of the separation parameter; identifying, from the plurality of mass spectra, a sequence of three or more intensity peaks that are ordered according to the separation parameter, wherein said identifying the sequence of intensity peaks comprises, selecting an initial intensity peak at an initial mass, and for each other intensity peak, selecting said intensity peak based on at least the mass of an adjacent intensity peak in the sequence of intensity peaks, the method further comprising, providing a mass trace, for a given emitted compound of the mass stream, from the identified sequence of intensity peaks.