Patent ID: 7482581

Claim:
A method of generating a mass spectrum from a Fourier Transform Mass Spectrometer (FTMS), comprising the steps of: (a) generating ions to be analysed by the FTMS; (b) determining, using processing means, an optimum number of ranges of generated ions to be captured in an FTMS measurement cell based upon a calibrant mass spectrum; (c) capturing a first quantity of the generated ions in an FTMS measurement cell, the first quantity including ions having a first range of m/z ratios; (d) detecting the captured ions within the said first range and producing a first output signal containing information regarding the m/z ratios of the ions in that first range; (e) capturing at least one further quantity of the generated ions in the measurement cell, the or each further quantity including ions having a corresponding further range of m/z ratios which is at least partly different to that of the first range and of any other further ranges which may have been captured in the measurement cell, the number of further quantities being based on the optimum number of ranges determined; (f) detecting the captured ions within the or each further range and producing a corresponding further output signal or signals containing information regarding the m/z ratios of the ions in the or each corresponding further range; and (g) combining, using said processing means, the first output signal with the at least one further output signal so as to produce a composite mass spectrum including m/z ratios from within each of the optimum number of ranges that are combined.