A computer implemented 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, wherein the mass spectrometry data are generated by analysis in a mass spectrometer, 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 three or more intensity peaks comprises: selecting an initial intensity peak of the sequence of intensity peaks at an initial mass, and selecting the other intensity peaks of the sequence of intensity peaks based on at least the mass of an adjacent intensity peak in the sequence of intensity peaks selected previously, wherein for each other intensity peak of the sequence of intensity peaks, said intensity peak is selected conditional on said intensity peak being at a respective mass that is within a respective range about a respective expected mass, the method further comprising providing a mass trace, for a given emitted compound of the mass stream, from the identified sequence of intensity peaks, characterized in that the respective expected mass is determined based on at least the mass of an adjacent intensity peak in the sequence of intensity peaks. 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 three or more intensity peaks comprises: selecting an initial intensity peak of the sequence of intensity peaks at an initial mass, and selecting the other intensity peaks of the sequence of intensity peaks based on at least the mass of an adjacent intensity peak in the sequence of intensity peaks selected previously, wherein for each other intensity peak of the sequence of intensity peaks, said intensity peak is selected conditional on said intensity peak being at a respective mass that is within a respective range about a respective expected mass, the method further comprising providing a mass trace, for a given emitted compound of the mass stream, from the identified sequence of intensity peaks, characterized in that the respective expected mass is determined based on at least the mass of an adjacent intensity peak in the sequence of intensity peaks. selecting an initial intensity peak of the sequence of intensity peaks at an initial mass, and selecting the other intensity peaks of the sequence of intensity peaks based on at least the mass of an adjacent intensity peak in the sequence of intensity peaks selected previously, wherein for each other intensity peak of the sequence of intensity peaks, said intensity peak is selected conditional on said intensity peak being at a respective mass that is within a respective range about a respective expected mass, the method further comprising providing a mass trace, for a given emitted compound of the mass stream, from the identified sequence of intensity peaks, characterized in that the respective expected mass is determined based on at least the mass of an adjacent intensity peak in the sequence of intensity peaks.