A method for identification of the monoisotopic mass or a parameter correlated to the mass of the isotopes of the isotope distribution of at least one species of molecules contained in a sample and/or originated from a sample by at least an ionization process includes measuring a mass spectrum of the sample with a mass spectrometer, dividing at least one range of measured m/z values of the mass spectrum into fractions, assigning at least some of the fractions to one processor of several provided processors, deducing for each of the at least one species of molecules an isotope distribution of their ions having a specific charge z, deducing from at least one deduced isotope distribution the monoisotopic mass or a parameter correlated to the mass of the isotopes of the isotope distribution of the species of molecules.