ABSTRACT
Alternatively, the quadrupole can be operated with only RF potentials applied to all four poles (rods). In this wide band-pass mode, no selection of ions occurs because the electric gate is, in effect, held open. Now, all ions produced in an ion source and injected into the front end of the quadrupole assembly traverse it and emerge from the other end. No ions are lost by striking the poles. Instead, the rod assembly acts to contain the ion beam, so it does not spread (the beam is collimated). Thus, all ions emerging from the quadrupole represent those produced in the ion source. The wide-and narrow band-pass modes can be switched very quickly, so at one instant the quadrupole may be letting through selected ions of m/z 100, m/z 200, m/z 300 or so on. After rapidly switching to the wide band-pass mode, all of the ions of m/z 100, 200, and 300 are allowed through the quadrupole together.
