Mass spectrometers that combine the high resolution and mass accuracy of Fourier transform mass spectrometry (FT-MS) with the ion storage and separation capabilities of quadrupole-quadrupole (Q-q) and linear ion trap mass spectrometry were recently introduced by Bruker Daltonics of Billerica, Mass., and Thermo Finnigan of San Jose, Calif. These instruments could accelerate the pace of protein identification in the rapidly expanding field of proteomics.
FT-MS is based on ion cyclotron resonance (ICR), in which ions generated by electrospray ionization or other methods are stored in an ICR cell in the presence of a magnetic field. The stored ions are excited with a radio frequency (RF) pulse, resulting in a cyclical motion with a frequency inversely proportional to the ions' mass-to-charge (m/z) ratio. The excited ions generate an image current that is then detected. Since each ion has a different frequency, the detected signal is a collection of the frequency components ...
