mass spectrometry sector field mass spectrometry Mass spectrometry where the sample ions are directed into magnetic field, the orientation of which is perpendicular to the beam. The magnetic field forces the charged particles into different circular trajectories, the radii of which depend on the strength of the magnetic field, the accelerating voltage, and the mass of the ion. SFMS sector field mass spectroscopy SF-MS magnetic sector mass spectrometry sector-field mass spectrometry sector-field mass spectroscopy CHMO:0000568