A method for operating a data processing system to find peaks in a mass spectrum that includes an ordered set of measurements of the abundances of species as a function of the mass/charge ratio of the species is disclosed. The method includes selecting a candidate blob that has a plurality of blob peaks from the mass spectrum. The data processing system selects a candidate blob peak for characterization. The candidate blob peak is approximated by a first species peak using a species peak model having a plurality of parameters by fitting the species peak model to a portion of the blob that has values that are substantially free of contributions from other species peaks that overlap with the first species peak and that are not represented by the species peak model. The first species peak is then subtracted from the candidate blob.