ELECTROSPRAY-IONIZATION FOURIER-TRANSFORM ION-CYCLOTRON RESONANCE AT 9.4 T

We present the first results from a new electrospray ionization Fourie r transform ion cyclotron resonance mass spectrometer operated at a ma gnetic field of 9.4 T (i.e. greater than or equal to 2.4 T higher than for any prior FTICR instrument). The 9.4 T instrument provides substa ntially Improved performance for large molecules (greater than or equa l to 50% increase in mass resolving power) and complex mixtures (great er than or equal to 100% increase in dynamic range) compared to lower- field (less than or equal to 6 T) instruments, The higher magnetic fie ld makes possible larger trapped-ion population without introduction o f significant space-charge effects such as spectral peak shift and/or distortion, and coalescence of closely-spaced resonances, For bovine u biquitin (8.6 kDa) we observe accurate relative isotopic abundances at a signal-to-noise ratio greater than 1000:1, whereas a complete nozzl e-skimmer dissociation electrospray ionization (ESI) FTICR mass spectr um of bovine carbonic anhydrase (29 kDa) is achieved from a single sca n with a signal-to-noise ratio of more than 250:1, Finally, we are abl e to obtain mass resolving power, m/Delta m >200 000, routinely for po rcine serum albumin (67 kDa). The present performance guides further m odifications of the instrument, which should lead to significant furth er improvements.