Electrospray ionization Fourier transform ion cyclotron resonance at 9.4 T

We present the first results from a new electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer operated at a magnetic 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 substantially Improved performance for large molecules (greater than or equal to 50% increase in mass resolving power) and complex mixtures (greater than or equal to 100% increase in dynamic range) compared to lower-field (less than or equal to 6 T) instruments, The higher magnetic field makes possible larger trapped-ion population without introduction of significant space-charge effects such as spectral peak shift and/or distortion, and coalescence of closely-spaced resonances, For bovine ubiquitin (8.6 kDa) we observe accurate relative isotopic abundances at a signal-to-noise ratio greater than 1000:1, whereas a complete nozzle-skimmer dissociation electrospray ionization (ESI) FTICR mass spectrum of bovine carbonic anhydrase (29 kDa) is achieved from a single scan with a signal-to-noise ratio of more than 250:1, Finally, we are able to obtain mass resolving power, m/Delta m >200 000, routinely for porcine serum albumin (67 kDa). The present performance guides further modifications of the instrument, which should lead to significant further improvements.