ION-MOLECULE REACTIONS FOR IMPROVED EFFECTIVE-MASS RESOLUTION IN ELECTROSPRAY MASS-SPECTROMETRY

Tandem mass spectrometry is shown to improve the effective mass resolu tion in electrospray mass spectrometry. The technique involves selecti ng a population of ions within a narrow range of mass-to-charge values and allowing the ions to undergo proton transfer reactions. The shift s in mass-to-charge ratios associated with product ions formed by prot on transfer allow for mass and charge assignment. The success of the t echnique relies on the relative enrichment of ions of a particular cha rge state that occurs in the mass-to-charge selection step. This appro ach can be used to extend the polymer mass range amenable to measureme nt, analyze mixtures that might otherwise be too complex for reliable mass measurements, and improve mass measurement precision when a mixtu re of cations is present within a given charge state. The technique is illustrated with a quadrupole ion trap using multiply-charged ions of cytochrome c, transfer ribonucleic acid from E. coli, strain W, and a synthetic deoxyribonucleic acid 30-mer.