Magnetic field focused ion accumulation for an internal bore liquid chromatography electrospray ionization Fourier transform ion cyclotron resonance mass spectrometer using a central trapping electrode

Presented is the application and evaluation of a magnetic field focusing central trapping electrode ion accumulation cell for a capillary liquid chromatography electrospray Fourier transform ion cyclotron (LC-ESI/FTICR) mass spectrometer. The ESI source and accumulation cell are located within the magnetic field to confine the radial motion of the ions, eliminating the need for elaborate focusing optics to transport the ions to the low-pressure analyzer cell for analysis. The central trapping electrode accumulation cell increases sensitivity by providing the necessary potential well in a confined volume to capture ions currently lost during the detection event of LC/FTICR experiments. With this electrode geometry the time needed to gate the ions into the analyzer cell is reduced and pump down delays are minimized. The decreased scan time improves LC resolution and increases the number of mass spectral scans per eluted component while maintaining appropriate base pressures for high performance ESI/FTICR. Results achieved with the central trapping electrode accumulation cell include an effective duty cycle increase from 10% to 40%, a S/N increase by a factor of 30, and a mass resolution increase of 80%.