Method and system of tandem mass spectrometry without primary mass selection for multicharged ions

A tandem mass spectrometer, comprising in combination:

• (a) a source (1) of multicharged primary ions to be analysed,
• (b) a device (3) for generating a primary mass spectrum of the primary ions, without dissociation, where said spectrum contains primary ion peaks of occurrence,
• (c) a set of correlation laws determined from the characteristic function values at the maxima of at least some of said primary mass peaks and from the charge values associated to said peaks, and that all possible multiplets of characteristic function values corresponding to multiplets of charged fragments resulting from the dissociation of parent primary ions of interest corresponding to said primary mass peaks have to meet,
• (d) a dissociation device (2) adapted to dissociate primary ions of interest associated to primary mass peaks, in order to obtain multiplets of charged fragments from each of said parent primary ions,
• (e) a device for generating and storing characteristic function values for the dissociated fragments,
• (f) a processing device for forming every potential multiplet of said characteristic function values, for identifying, from amongst said potential multiplets, the multiplets which meet a proximity criterion in relation to said correlation laws, in order to determine the real multiplets of charged fragments corresponding to the parent primary ions, and for generating dissociation mass spectra corresponding respectively to the parent primary ions of interest, comprising the peaks associated to the real multiplets of identified fragments.

A computer readable storage medium storing a computer program for a mass spectrometry system comprising a mass spectrometer having a known characteristic function of the mass-to-charge ratio of ions, said computer program including a set of instructions which when executed by a digital computer perform the following steps:

• (a) controlling the system so that it generates, from a source of multicharged primary ions to be analysed, a primary mass spectrum of said primary ions, without dissociation, where this spectrum contains peaks of occurrences of primary ions,
• (b) performing an acquisition of the data of this spectrum, including characteristic function values at the maxima of at least some of the primary mass peaks and from the charge values associated to said peaks,
• (c) from said data, determining correlation laws that all possible multiplets of characteristic function values corresponding to multiplets of charged fragments resulting from the dissociation of parent primary ions of interest corresponding to said primary mass peaks have to meet,
• (d) controlling the system so that it generates the concurrent dissociation of primary ions of interest associated to primary mass peaks so as to obtain multiplets of charged fragments from each of said parent primary ions, and to generate characteristic function values for said dissociated fragments,
• (e) forming every potential multiplet of said characteristic function value,
• (f) identifying, from amongst said potential multiplets, the multiplets which meet a proximity criterion in relation to said correlation laws, in order to determine the real multiplets of charged fragments corresponding to the parent primary ions, and
• (g) generating dissociation mass spectra corresponding respectively to the parent primary ions of interest, comprising the peaks associated to the real multiplets of identified fragments.