A method performed on a computer to identify peaks generated by different physical ions in a solution including a certain concentration of at least one substance by analyzing mass and intensity coordinates of all peaks, measured with errors, coming from a set of mass spectra data files, said method comprising, - reading coordinates of a peak from a first mass spectrum data file in the set of mass spectra data files; - selecting from each said mass spectrum data file other than the first mass spectrum data file, peak coordinates which are close to the read peak coordinates from the first mass spectrum, by computing a first distance function qualifying a proximity between two peaks; - determining the highest scored sequence of peaks comprising the read peak from the first mass spectrum and one selected peak from each other mass spectrum by computing a first score function qualifying the likelihood that all peaks in the sequence have been generated by the same type of physical ion; - storing the highest scored sequence only if the ratio highest scored / second highest scored sequence is above a limit ratio; - reading coordinates of one other peak from said first mass spectrum data file and executing the preceding selecting, determining and storing steps until all the peaks from said mass spectrum are read; - repeating the preceding steps on further sets of mass spectra, said first and further sets of mass spectra corresponding to different concentrations; - computing average mass-intensity peak coordinates for each stored sequence resulting from execution of the preceding steps for each solution concentration and obtaining a series of virtual peaks per each concentration; - applying the first five reading, selecting, determining, storing and reading steps to the set of virtual mass spectra, each virtual mass spectrum corresponding to one concentration, each virtual mass spectrum comprising the computed series of virtual peaks, using a second distance function between two peaks which depends on the mass of the peaks and a second scoring function which depends on a combination of the mass of the peaks and the peak concentration-intensity correlation, the resulting sequences being the peaks corresponding to an ion in the different 'virtual mass spectra', each 'virtual mass spectrum' corresponding to one solution concentration. - reading coordinates of a peak from a first mass spectrum data file in the set of mass spectra data files; - selecting from each said mass spectrum data file other than the first mass spectrum data file, peak coordinates which are close to the read peak coordinates from the first mass spectrum, by computing a first distance function qualifying a proximity between two peaks; - determining the highest scored sequence of peaks comprising the read peak from the first mass spectrum and one selected peak from each other mass spectrum by computing a first score function qualifying the likelihood that all peaks in the sequence have been generated by the same type of physical ion; - storing the highest scored sequence only if the ratio highest scored / second highest scored sequence is above a limit ratio; - reading coordinates of one other peak from said first mass spectrum data file and executing the preceding selecting, determining and storing steps until all the peaks from said mass spectrum are read; - repeating the preceding steps on further sets of mass spectra, said first and further sets of mass spectra corresponding to different concentrations; - computing average mass-intensity peak coordinates for each stored sequence resulting from execution of the preceding steps for each solution concentration and obtaining a series of virtual peaks per each concentration; - applying the first five reading, selecting, determining, storing and reading steps to the set of virtual mass spectra, each virtual mass spectrum corresponding to one concentration, each virtual mass spectrum comprising the computed series of virtual peaks, using a second distance function between two peaks which depends on the mass of the peaks and a second scoring function which depends on a combination of the mass of the peaks and the peak concentration-intensity correlation, the resulting sequences being the peaks corresponding to an ion in the different 'virtual mass spectra', each 'virtual mass spectrum' corresponding to one solution concentration.