Method for electrospray ionization mass spectroscopy of multiply-charged biomolecular ions

A method for electrospray ionization mass spectrometry, comprising:

• a) preparing a sample solution comprising biomolecules;
• b) performing electrospray ionization of the sample solution to produce ionized biomolecules;
• c) performing mass spectrometry of the ionized biomolecules using a mass spectrometer to produce mass spectrum data;
• and
• d) processing by a data processor the mass spectrum data to produce in a fully automated manner absolute mass distribution data of the biomolecules, wherein processing comprises:
• i) generating from the mass spectrum data a short time Fourier transform (STFT) spectrogram of frequency versus mass-to-charge (m/z);
• ii) grouping a series of signal peaks (local magnitude maxima) at integer-value frequencies in the STFT spectrogram;
• iii) assigning a charge state value to selected pixels in the STFT spectrogram associated with the grouped series of signal peaks;
• iv) generating a preliminary deconvolved mass spectrum by applying an inverse STFT transform to the selected pixels in the STFT spectrogram associated with the grouped series of signal peaks, and converting m/z values to mass values;
• and
• v) refining the preliminary deconvolved spectrum to produce the absolute mass distribution data by performing a secondary STFT transform on the preliminary deconvolved spectrum, excluding signal data at non-integer frequencies, and performing a subsequent inverse STFT transform.