Patent ID: 8481924

Claim:
A method of identifying precursor ion species from their fragments comprising: (a) determining a quantity indicative of the mass of a plurality of precursor ion species; (b) fragmenting the ions of the plurality of precursor ion species to form a plurality of fragment ions derived from the plurality of precursor ions; (c) mass analysing together, the fragment ions derived from multiple precursor ion species; (d) assigning one or more sample sets of multiple fragment ion species to a particular one of the plurality of precursor ion species, the or each sample set including fragment ion species whose combined mass as determined in step (c)) corresponds with that of the particular one of the precursor sample ion species to which those fragment ion species are assigned; (e) for one or more of the precursor ion species, forwarding sample data identifying (i) the mass of the particular precursor sample ion species identified in step (a), and (ii) the mass of the multiple fragment ion species in the or each assigned sample set for that particular precursor ion species, to a comparing means, for comparison of quantities indicative of the mass of the precursor and assigned fragment ion species with quantities representative of the mass of ions in one or more reference sets of reference fragment ion data and reference precursor ion data respectively; and (f) receiving, from the comparing means, information indicative of the results of the said comparison.