Patent Document ID: 20030109990
Application ID: 10220930
Patent Flag: 0

Claim One:
1. A method for determining the monoisotopic mass of a sample molecule, based on at least a section of an experimentally obtained mass spectrum ( 300 ) representative of the sample molecule, by comparing said experimentally obtained mass spectrum ( 300 ) with a model mass spectrum for said sample molecule, comprising the steps of a) determining the highest correlation between said spectra, by i) assuming values for one or more unknown parameters including the monoisotopic mass and charge state (Z) of said sample molecule, said parameters describing the peak shape of a model mass spectrum of said sample molecule, ii) calculating a model mass spectrum, including the position of a model monoisotopic mass peak, said model mass spectrum representing an expected spectrum for a theoretical model molecule representative of said assumed values for the unknown parameters of the sample molecule ( 301 - 304 ); iii) determining a position of said model mass spectrum along the m/Z axis of the experimentally obtained spectrum that provides the best agreement with the experimental mass spectrum using the cross correlation method ( 305 - 309 ) by incrementally moving said spectrum along the m/Z axis of the experimentally obtained spectrum; repeating steps i)-iii) a selected number of times ( 310 ), each time calculating a modified model mass spectrum based on a modified assumption of the values of said unknown parameters; b) selecting the model spectrum having the highest correlation, and taking the monoisotopic mass associated therewith as the true monoisotopic mass for the sample molecule.